中英文转换在线翻译器
12-Bit A/D Converter
CIRCUIT OPERATION The AD574A is a complete 12-bit A/D converter which requires no external components to provide the complete successive approximation analog-to-digital conversion function.A block diagram of the AD574A is shown in Figure 1.Figure 1.Block Diagram of AD574A 12-Bit A-to-D Converter
When the control section is commanded to initiate a conversion(as described later), it enables the clock and resets the successiveapproximation register(SAR)to all zeros.Once a conversion cycle has begun, it cannot be stopped or restarted and data is not available from the output buffers.The SAR, timed by the clock, will sequence through the conversion cycle and return an end-of-convert flag to the control section.The control section will then disable the clock, bring the output status flag low, and enable control functions to allow data read functions by external command.During the conversion cycle, the internal 12-bit current output DAC is sequenced by the SAR from the most significant bit(MSB)to least significant bit(LSB)to provide an output current which accurately balances the input signal current through the 5kΩ(or10kΩ)input resistor.The comparator determines whether the addition of each successively-weighted bit current causes the DAC current sum to be greater or less than the input current;if the sum is less, the bit is left on;if more, the bit is turned off.After testing all the bits, the SAR contains a 12-bit binary code which accurately represents the input signal to within 1/2 LSB.The temperature-compensated buried Zener reference provides the primary voltage reference to the DAC and guarantees excellent stability with both time and temperature.The reference is trimmed to 10.00 volts 0.2%;it can supply up to 1.5 mA to an external load in addition to the requirements of the reference input resistor(0.5 mA)and bipolar offset resistor(1 mA)when the AD574A is powered from 15 V supplies.If the AD574A is used with 12 V supplies, or if external current must be supplied over the full temperature range, an external buffer amplifier is recommended.Any external load on the AD574A reference must remain constant during conversion.The thin-film application resistors are trimmed to match the full-scale output current of the DAC.There are two 5 kinput scaling resistors to allow either a 10 volt or 20 volt span.The 10 kbipolar offset resistor is grounded for unipolar operation and connected to the 10 volt reference for bipolar operation.DRIVING THE AD574 ANALOG INPUT
Figure 2.Op Amp – AD574A Interface
The output impedance of an op amp has an open-loop value which, in a closed loop, is divided by the loop gain available at the frequency of interest.The amplifier should have acceptable loop gain at 500 kHz for use with the AD574A.To check whether the output properties of a signal source are suitable, monitor the AD574’s input with an oscilloscope while a conversion is in progress.Each of the 12 disturbances should subside in sorless.For applications involving the use of a sample-and-hold amplifier, the AD585 is recommended.The AD711 or AD544 op amps are recommended for dc applications.SAMPLE-AND-HOLD AMPLIFIERS Although the conversion time of the AD574A is a maximum of 35 s, to achieve accurate 12-bit conversions of frequencies greater than a few Hz requires the use of a sample-and-hold amplifier(SHA).If the voltage of the analog input signal driving the AD574A changes by more than 1/2 LSB over the time interval needed to make a conversion, then the input requires a SHA.The AD585 is a high linearity SHA capable of directly driving the analog input of the AD574A.The AD585’s fast acquisition time, low aperture and low aperture jitter are ideally suited for high-speed data acquisition systems.Consider the AD574A converter with a 35 s conversion time and an input signal of 10 V p-p: the maximum frequency which may be applied to achieve rated accuracy is 1.5 Hz.However, with the addition of an AD585, as shown in Figure 3, the maximum frequency increases to 26 kHz.The AD585’s low output impedance, fast-loop response, and low droop maintain 12-bits of accuracy under the changing load conditions that occur during a conversion, making it suitable for use in high accuracy conversion systems.Many other SHAs cannot achieve 12-bits of accuracy and can thus compromise a system.The AD585 is recommended for AD574A applications requiring a sample and hold.Figure 3.AD574A with AD585 Sample and Hold
SUPPLY DECOUPLING AND LAYOUT CONSIDERATIONS It is critically important that the AD574A power supplies be filtered, well regulated, and free from high frequency noise.Use of noisy supplies will cause unstable output codes.Switching power supplies are not recommended for circuits attempting to achieve 12-bit accuracy unless great care is used in filtering any switching spikes present in the output.Remember that a few millivolts of noise represents several counts of error in a 12-bit ADC.Circuit layout should attempt to locate the AD574A, associated analog input circuitry, and interconnections as far as possible from logic circuitry.For this reason, the use of wire-wrap circuit construction is not recommended.Careful printed circuit construction is preferred.UNIPOLAR RANGE CONNECTIONS FOR THE AD574A The AD574A contains all the active components required to perform a complete 12-bit A/D conversion.Thus, for most situations, all that is necessary is connection of the power supplies(+5 V, +12 V/+15 V and –12 V/–15 V), the analog input, and the conversion initiation command, as discussed on the next page.Analog input connections and calibration are easily accomplished;the unipolar operating mode is shown in Figure 4.Figure 4.Unipolar Input Connections
All of the thin-film application resistors of the AD574A are trimmed for absolute calibration.Therefore, in many applications, no calibration trimming will be required.The absolute accuracy for each grade is given in the specification tables.For example, if no trims are used, the AD574AK guarantees 1 LSB max zero offset error and 0.25%(10 LSB)max full-scale error.(Typical full-scale error is 2 LSB.)If the offset trim is not required, Pin 12 can be connected directly to Pin 9;the two resistors and trimmer for Pin 12 are then not needed.If the full-scale trim is not needed, a 50 1% metal film resistor should be connected between Pin 8 and Pin 10.The analog input is connected between Pin 13 and Pin 9 for a 0 V to +10 V input range, between 14 and Pin 9 for a 0 V to +20 V input range.The AD574A easily accommodates an input signal beyond the supplies.For the 10 volt span input, the LSB has a nominal value of 2.44 mV;for the 20 volt span, 4.88 mV.If a 10.24 V range is desired(nominal 2.5 mV/bit), the gain trimmer(R2)should be replaced by a 50Ωesistor, and a 200Ωtrimmer inserted in series with the analog input to Pin 13 for a full-scale range of 20.48 V(5 mV/bit), use a 500 trimmer into Pin 14.The gain trim described below is now done with these trimmers.The nominal input impedance into Pin 13 is 5kΩ, and 10kΩinto Pin 14.UNIPOLAR CALIBRATION The AD574A is intended to have a nominal 1/2 LSB offset so that the exact analog input for a given code will be in the middle of that code(halfway between the transitions to the codes above and below it).Thus, the first transition(from 0000 0000 0000 to 0000 0000 0001)will occur for an input level of +1/2 LSB(1.22 mV for 10 V range).If Pin 12 is connected to Pin 9, the unit will behave in this manner, within specifications.If the offset trim(R1)is used, it should be trimmed as above, although a different offset can be set for a particular system requirement.This circuit will give approximately 15 mV of offset trim range.The full-scale trim is done by applying a signal 1/2 LSB below the nominal full scale(9.9963 for a 10 V range).Trim R2 to give the last transition(1111 1111 1110 to 1111 1111 1111).BIPOLAR OPERATION The connections for bipolar ranges are shown in Figure 5.Again, as for the unipolar ranges, if the offset and gain specifications are sufficient, one or both of the trimmers shown can be replaced by a 50 1% fixed resistor.Bipolar calibration is similar to unipolar calibration.Figure 5.Bipolar Input Connections
CONTROL LOGIC The AD574A contains on-chip logic to provide conversion initiation and data read operations from signals commonly available in microprocessor systems.Figure 6 shows the internal logic circuitry of the AD574A.The control signals CE, CS, and R/C control the operation of the converter.The state of R/C when CE and CS are both asserted determines whether a data read(R/C = 1)or a convert(R/C = 0)is in progress.The register control inputs AO and 12/8 control conversion length and data format.The AO line is usually tied to the least significant bit of the address bus.If a conversion is started with AO low, a full 12-bit conversion cycleis initiated.If AO is high during a convert start, a shorter 8-bit conversion cycle results.During data read operations, AO determines whether the three-state buffers containing the 8 MSBs of the conversion result(AO = 0)or the 4 LSBs(AO = 1)are enabled.The 12/8 pin determines whether the output data is to be organized as two 8-bit words(12/8 tied to DIGITAL COMMON)or a single 12-bit word(12/8 tied to VLOGIC).The 12/8 pin is not TTL-compatible and must be hard-wired to either VLOGIC or DIGITAL COMMON.In the 8-bit mode, the byte addressed when AO is high contains the 4 LSBs from the conversion followed by four trailing zeroes.This organization allows the data lines to be overlapped for direct interface to 8-bit buses without the need for external three-state buffers.It is not recommended that AO change state during a data read operation.Asymmetrical enable and disable times of the three-state buffers could cause internal bus contention resulting in potential damage to the AD574A.Figure 6.AD574A Control Logic An output signal, STS, indicates the status of the converter.STS goes high at the beginning of a conversion and returns low when the conversion cycle is complete.TIMING The AD574A is easily interfaced to a wide variety of microprocessors and other digital systems.The following discussion of the timing requirements of the AD574A control signals should provide the system designer with useful insight into the operation of the device.Figure 7 shows a complete timing diagram for the AD574A convert start operation.R/C should be low before both CE and CS are asserted;if R/C is high, a read operation will momentarily occur, possibly resulting in system bus contention.Either CE or CS may be used to initiate a conversion;however, use of CE is recommended since it includes one less propagation delay than CS and is the faster input.In Figure 7, CE is used to initiate the conversion.Figure 7
Once a conversion is started and the STS line goes high, convert start commands will be ignored until the conversion cycle is complete.The output data buffers cannot be enabled during conversion.Figure 8 shows the timing for data read operations.During data read operations, access time is measured from the point where CE and R/C both are high(assuming CS is already low).If CS is used to enable the device, access time is extended by 100 ns.Figure 8.Read Cycle Timing
In the 8-bit bus interface mode(12/8 input wired to DIGITAL COMMON), the address bit, AO, must be stable at least 150 ns prior to CE going high and must remain stable during the entire read cycle.If AO is allowed to change, damage to the AD574A output buffers may result.“STAND-ALONE” OPERATION
The AD574A can be used in a ―stand-alone‖ mode, which is useful in systems with dedicated input ports available and thus not requiring full bus interface capability.In this mode, CE and 12/8 are wired high, CS and AO are wired low, and conversion is controlled by R/C.The three-state buffers are enabled when R/C is high and a conversion starts when R/C goes low.This allows two possible control signals—a high pulse or a low pulse.Operation with a low pulse is shown in Figure 11.In this case, the outputs are forced into the high impedance state in response to the falling edge of R/C and return to valid logic levels after the conversion cycle is completed.The STS line goes high 600 ns after R/C goes low and returns low 300 ns after data is valid.Figure 11.Low Pulse for R/C—Outputs Enabled After Conversion
If conversion is initiated by a high pulse as shown in Figure 12, the data lines are enabled during the time when R/C is high.The falling edge of R/C starts the next conversion, and the data lines return to three-state(and remain three-state)until the next high pulse of R/C.Figure 12.High Pulse for R/C—Outputs Enabled While R/C High, Otherwise High-Z
Usually the low pulse for R/C stand-alone mode will be used.Figure 13 illustrates a typical stand-alone configuration for 8086 type processors.The addition of the 74F/S374 latches improves bus access/release times and helps minimize digital feedthrough to the analog portion of the converter.INTERFACING THE AD574A TO MICROPROCESSORS The control logic of the AD574A makes direct connection to most microprocessor system buses possible.While it is impossible to describe the details of the interface connections for every microprocessor type, several representative examples will be described here.GENERAL A/D CONVERTER INTERFACE CONSIDERATIONS A typical A/D converter interface routine involves several operations.First, a write to the ADC address initiates a conversion.The processor must then wait for the conversion cycle to complete, since most ADCs take longer than one instruction cycle to complete a conversion.Valid data can, of course, only be read after the conversion is complete.The AD574A provides an output signal(STS)which indicates when a conversion is in progress.This signal can be polled by the processor by reading it through an external three-state buffer(or other input port).The STS signal can also be used to generate an interrupt upon completion of conversion, if the system timing requirements are critical(bear in mind that the maximum conversion time of the AD574A is only 35 microseconds)and the processor has other tasks to perform during the ADC conversion cycle.Another possible time-out method is to assume that the ADC will take 35 microseconds to convert, and insert a sufficient number of ―do-nothing‖ instructions to ensure that 35 microseconds of processor time is consumed
Once it is established that the conversion is finished, the data can be read.In the case of an ADC of 8-bit resolution(or less), a single data read operation is sufficient.In the case of converters with more data bits than are available on the bus, a choice of data formats is required, and multiple read operations are needed.The AD574A includes internal logic to permit direct interface to 8-bit or 16-bit data buses, selected by connection of the 12/8 input.In 16-bit bus applications(12/8 high)the data lines(DB11 through DB0)may be connected to either the 12 most significant or 12 least significant bits of the data bus.The remaining four bits should be masked in software.The interface to an 8-bit data bus(12/8 low)is done in a left-justified format.The even address(A0 low)contains the 8 MSBs(DB11 through DB4).The odd address(A0 high)contains the 4 LSBs(DB3 through DB0)in the upper half of the byte, followed by four trailing zeroes, thus eliminating bit masking instructions.SPECIFIC PROCESSOR INTERFACE EXAMPLES Z-80 System Interface The AD574A may be interfaced to the Z-80 processor in an I/O or memory mapped configuration.Figure 15 illustrates an I/O or mapped configuration.The Z-80 uses address lines A0–A7 to decode the I/O port address.An interesting feature of the Z-80 is that during I/O operations a single wait state is automatically inserted, allowing the AD574A to be used with Z-80 processors having clock speeds up to 4 MHz.For applications faster than 4 MHz use the wait state generator in Figure 16.In a memory mapped configuration the AD574A may be interfaced to Z-80 processors with clock speeds of up to 2.5 MHz.附录E 中文翻译
12位-AD574A转换器
电路工作原理
AD574A是一个完善的12位A/D转换器，不需要外部组件提供完全的逐步逼近模拟数字转换功能。图1所示为AD574A的方块结构图。
图1 AD574A的方块结构图
当控制部分收到初始化转换命令（后边会叙述）时，会开启时钟并把连续逼近寄存器（SAR）全部置零。一旦转换周期开始，它就不能终止或重新开始，也不能从输出缓冲中读数。时钟控制SAR寄存器的时序，SAR会安排好转换周期的顺序并向控制部分返回一个“转换结束”（end-of-convert）标志。接着，控制部分停止时钟，把输出状态标志位置低，并允许控制函数，以便外部命令可以执行数据读取功能。
在转换周期期间, 内部12 位当前的产品DAC 由SAR 程序化从最高位(MSB)对最低有效位(LSB)通过5 k(或10k)输入电阻器提供准确地平衡输入信号。比较器确定位电流的连续增大是否造成了DAC当前总电流比输入电流增大或者减小;如果总电流较小，此位被留下;如果总电流较大，位被关闭。在测试完所有位以后，SAR包含了准确表示输入信号在+1/2 LSB之内的12位二进制编码。温度补偿是外部提供给DAC基准电压并保证准确的转换的时间和温度的稳定性。基准在10.000.2%伏之间平衡，当AD574A使用15伏电源时，除了按要求向参考输入电阻提供0.5mA，向双极偏移电阻提供1mA电流外，它可以给外部负载提供提供高至1.5mA的电流。如果AD574A使用12伏电源，或者外部电流必须在全部温度范围内提供，那么我们推荐使用一个外部的缓冲放大器。任何在AD574A参考手册上的外部负载都必须在转换过程中保持稳定。要调整薄膜应用电容以匹配DAC（数模转换器）的实比例输出电流。有两个5千欧的输入测量电阻允许10伏或20伏的区间。10千欧的双极偏移电容接地用于单极操作，或连接到10伏参考电压上用于双极性操作。
AD574模拟输入电压
图2 OP放大器与AD574连接
OP放大器的输出阻抗有一个开环值，在一个封闭回路中，这个值被回路增益（由增加的频率产生）等分。放大器应该至少拥有500kHz的回路增益才能和AD574A一起使用。要检查信号源的输出特性是否合适，就要在转换进行中使用示波镜监控AD574的输入端。每12个干扰应该在1秒以内衰减。
关于取样—保持器的应用，我们推荐AD585型号。我们推荐让AD711型号和AD544型号取样—保持器应在直流电下工作。
虽然AD574A的转换时间最高为35秒，但为了能够实现几个赫兹的频率的精确12位转换还是需要使用采样－保持放大器（SHA）的。如果一个驱动AD574A的模拟输入信号电压在转换所需的计时周期中变化超过LSB的一半，那么输入端就需要一个SHA。
AD585是一种高线性的采样－保持放大器（SHA），它能够直接驱动AD574A的模拟输入端。AD585的快速采集时间、低孔径和低孔径抖动都很好地使用于高速数据采集系统。考虑到AD574A的转换时间为35秒，并且拥有10Vp-p的输入信号，这是能够实现1.5Hz精确转换时所能用的最高频率。如图3所示，加上AD585后，最高频率增加到了26kHz。
AD585的低输出阻抗、快速连环反应和低损耗能够在变化的周期性负荷工况下维持12位准确性，使它适当用于高精确度转换。许多其他SHAs达不到12位转换的准确性，并且可能因而减弱系统。AD585被推荐应用于AD574A的采样与保持。
图3 带采样保持器AD585的AD574A
AD574A 电源的滤波、良好地校准和远离高频噪声是异常重要的.。噪声补偿的使用会造成不稳定的输出信号。除非特别要求滤掉输出端的电火花，交换式电源电路建议达到12比特的精确度。注意： 一点点毫伏的噪声就代表着12比特ADC（电源）的巨大误差。
电路布局应该尝试定位AD574A,与之相连的相似物输入电路,并使其从逻辑电路上尽可能连接起来.因为这个原因,不推荐使用线路电路结构.应该选择好的印刷的电路体系.AD574A处理单极性信号
AD574A包括了所有进行完全12位AD转换所需的活动组件。这样，在大多数情况下，所需的只是电源连接（+5 V, +12 V/+15 V 和 –12 V/–15 V）、模拟输入以及转换初始化命令，下页会讨论到。模拟输入连接和校准都很容易完成。单极操作模式如图4所示。
图4
AD574A所有的薄膜应用程序电阻是通过绝对刻度来衡量的。因此在许多应用程序中，并不需要刻度平衡。规格表给出了每个等级的绝对精度。例如，如果没有应用区标，AD574AK保证1LSB最大零偏移误差和0.25%(10LSB)最大满额误差。（通常满额误差是2 LSB）。如果不允许使用这个弯管平衡的话，pin 12 可以直接同pin 9连接；pin 12 的这两个电阻器和这个微调电容器就不需要了。如果不允许使用完整的平衡，应该在pin 8和pin 10之间连接一个xxxx金属薄膜微调电容器。
此器件在输入电压0到10伏连接时须接脚9和脚13,当输入电压在0到20伏之间时,应从脚14和脚9引入。AD574A提供输入信号补偿，输入电压在10伏以内时理论值是2.44mV,在输入电压在20伏以内时理论值是2.44mV
如果电压达到10.24(也就是2.5mv/bit), 增益可调电阻就必须调整为50.一个200Ω可变电阻串连到模拟输入引脚13其满刻度值为20.48V(5 mV/bit),用500Ω的可变电阻串连到模拟输入引脚14.下述增益的调整用这些可变电阻完成.引脚13的名义输入阻抗为5 kΩ, 而插脚14的名义输入阻抗为10kΩ。
单极性输入
AD574A拥有一个名义上是LSB一半的偏移量，以便对一个给定编码的准确模拟输入可以正好处于这个编码的中央（在其前后各有一半的编码转换）。这样，第一个转换（从0000 0000 0000到0000 0000 0001）会在输入电平为+1/2LSB（对于10V的范围来说是1.22mV）时发生。
如果第12脚连在第9脚上，那么单元将在规格之内按此方式工作。如果使用了偏移调整（R1），虽然可以针对特定的系统要求设置不同的偏移量，但也应该按上述方法调整。这个电路会给出大约15mV的偏移调整范围。
满量程调整适用于一个信号在满量程下产生1/2 LSB线性误差，也就是对于10V范围来说是9.9963。调整R2来实现最后一个转换（1111 1111 1110到1111 1111 1111）
双极性输入
双极的联系范围如图5。还有，就单极的范围，如果输出量与增加量的数据充足的话，一个电容器或者两个都可以拿一个50±1%的固定电阻来代替。单极标准与双极标准是相似的。
图5 逻辑控制
AD574A包含了芯片上逻辑，可以通过微处理器中通常存在的信号中提供开始转换和读取转换结果操作‖ 如图6是AD574A的内部逻辑电路。
控制信号CE、CS, 和R/C 控制交换器的操作。R/C 的状态由CE 和CS 两个信号的加入来确定进行数据读取(R/C = 1)或数据转换(R/C = 0)。记数器控制输入AO ,12/8 控制转换长度和数据格式。AO 线通常被连结到地址总线的最低有效位。如果AO置低(电位)开始, 按12 位A/D进行转换。当12/8=1时，12位数据线一次读出，主要用于16位微机系统；12/8=0时，可与8位机接口。此引脚输入为高电平时，12位数据并行输出；当此引脚为低电平时，与引脚A0配合，把12位数据分两次输出。12/8的引脚接DIGITAL COMMON输出8位数据12/8引脚接VLOGIC输出12位数据。12/8的引脚不与TTL兼容的，必须和vlogic或者digital连接，在8位模式下，当Ao置高的时候，低4位加上尾随4个0有效。在不需要内部3态缓冲器的情况下，该结构允许直接接口的8位数据流重叠。在读取转换数据操作时不建议ao改变。三态缓冲器不对称的允许与阻止时间可能造成内部总线冲突,对AD574A造成潜在危害.图6
STS这个输出信号表明了转换器的状况。STS值在转换开始时升高，在转换过程完成后降低回原样。
AD574A 容易联接于多种微处理器和其他数字化系统。下列AD574A控制信号的计时要求的讨论应该为系统设计者提供有用的对设备的操作了解。
图7
图7显示的是完整的AD574A运作时间矢量图表.坐标轴R/C在CE和CS被捕获之前都应较低;如果R/C显示较高,操作提示会立即发生,并可能引发系统争用.无论CE还是CS都能被用来转换.但是,我们推荐使用CE,因为它比CS有更少的系统延迟,并且能被较快地 输入.在图表7,CE被用来转换.一旦转换开始STS置成高位，直到转换循环完成,转换开始命令将被忽略。直到转换周期是完全的。在转换期间，输出数据缓冲无效。
图8给出了数据读取操作时间状况,在数据读取过程中, 当CE和R/C都处于高电平(假定CS已经处于低电平)的时候,开始测量访问时间.如果这时CS能够使得设备工作, 访问时间可延长100纳秒.图8 在8位的总线接线模式中（和数字公用区连线的12/8 输出），地址位AO，必须在CE升高的150毫秒之前和整个读取循环中保持稳定。如果允许AO变化，将会导致对AD574A输出缓存区的损坏。
AD5474A单机操作
AD5474A可以“独立”模式使用，它是系统里很好用的、可用的和专用的端口，以这种方式不需要用总线连接。按这方式，CE和12/8置成高位，CS和AO置成低位，而转化由RC控制。当RC置成高位时，三态缓冲器启动，当RC置成低位时开始转换。其允许两种控制信号一种高电位脉冲，低高电位脉冲。由如图11所示的低脉冲操作。在这种情况下R/C下降沿的输出响应被强制为高阻状态，在一个转换周期结束后置回有效逻辑。STS线在R/C变为低电平600ns后变为高电平，当数据有效300ns后恢复低电平。
图9
如果转换是由如图12所示的高电平脉冲所初始化的，那么在R/C为高电平时，数据链是被允许的。R/C的下降沿启动下一个转换，并且数据链返回到三态（并一直保持三态），知道下一个R/C高电平脉冲出现。
图10
通常应用R/C单机模式下的低脉冲。图13阐明了典型的8086型处理机的单机构造。额外的74F/S374 插销提高了总线的访问/放行次数并协助简化转炉数-模部分的连接线。
图11
AD574与单片机接口
AD574A的控制逻辑使得绝大多数情况下和微处理器系统总线直接连线变成可能。然而它不可能描述出每一种微处理器类型的接口连接的所有细节，下面将举几个具有代表性的例子。
典型的数模转换器接口程序序列涉及以下几步：首先, 在初始化会话的时候，地址被写进数模转换。处理器必须等待会话周期的结束，因为多数数模转换器需要一个以上的指令周期来完成会话操作。当然，有效数据只有在会话结束后才能被读取。AD574A 提供信号端输出(STS)，它能指示会话过程。这个信号可以由处理器通过读取外部三态缓冲（或其它输入端口）获得。如果系统的计时要求非常严格（请记住AD574A的最大转换时间只有35毫秒）并且处理器在ADC转换周期中有其它任务要做的话，这个STS信号同样可以用于产生一个中断信号传递给转换过程。另一种可行的延时方法是，先假设模数转换器会消耗35微秒来进行转换，然后插入足够多的空指令来保证处理器消耗掉35微秒的时间。
一旦建立,即完成转换,可以读取数据.在8位(或数位更少)ADC的情况下,单次读数运行即已足够.在转换器数位多于总线可使用数位的情况下,须选择数据格式,需进行多重读数运行.AD574A含有内部逻辑(器),允许通过选择连接12/8输入而直接到8位或多或16位数据总线界面上。在采用16位数据总线时,(12/8 高)数据总线(DB11 通过 DB0)既可以连接到数据总线的12位有效位或12位无效位。剩余4位应用软件将其掩蔽.到8位数据总线的界面是采用左优格式来实现的。在数位的上半部偶数地址(A0 低)包含 8 MSBs(DB11 通过 DB4).。奇数地址(A0 高)包含 4 LSBs(DB3 through DB0),后面跟有4个零,从而消除数位掩蔽指令.AD574A可以在输入/输出或者储存映像结构中被接线到Z-80 处理机上。图15阐明了一个输入/输出或者映像结构。Z-80使用A0–A7 地址线来解码输入/输出端口地址。
关键词：高职学校,英文翻译,词类转换,语言能力
英文翻译是英语与汉语两种语言之间的转换, 要求翻译者不仅必须具有英语和汉语两门语言表达的基础知识和基本表达技巧, 而且还必须具备相应的两门语言的文化背景知识, 并非是对词类、词性及语言成分进行对应转换, 而是要运用一定的语言学理论分析, 紧密结合人们日常生活具体实际, 结合英语中名词、动词、形容词等词性特征与语境要求, 遵循科学的翻译规则对相应的词语进行恰当的选择与组合, 并综合把握好语言风格与思想情感, 促使两种语言所表达出来的思想内容与情感含意一致起来, 实现在语言表达形式上达到更加准确、流畅与顺达目标, 最终达到英文翻译“信”“达”“雅”的完美诠释。
一、英语翻译中词类转换概述
立足于语言视角分析, 每一门语言都具有自身所独特的词性特质, 每一个词汇在语句中所处的位置、所担任的成分角色、所具有功能作用都是有源可溯、有“法”可依的。而从转喻理论视角着眼, 英汉语言翻译中词类转换不仅是英语专业教学中的始终关注的热点, 而且也是当前国内外语言研究专家学者重点关注的问题。就英语翻译中词类转换本身来说, 对词类进行转换就是基于不改变词汇相关形态的同时, 对它们所表达的涵义进行词性转换, 比如将名词转换成为动词、形容词或副词, 将动词转换成为形容词或副词等。例如, 对于“skin”这个词, 通常是表达为名词“皮”的意思, 而亦可将其转换成为动词“剥皮”, 比如在“Could you skin the banana?”这个句子当中, 就是将名词转换成动词的一个经典案例。
二、英语翻译中词类转换技巧剖析
多年来高职学校英语专业教学实践表明, 许多学生在英文翻译实践活动中, 常常拘泥于原文的篇幅、章法、句式架构, 不能很好地跳出英文语法与句法限定的框架, 从而导致进入生搬硬套的翻译轨道上来, 轻则引发句式不通顺、上下文不连贯现象产生, 重则导致词性与词义颠倒混乱, 翻译不符合语境要求, 甚至不但不能很好地与英文本应表达的含义相一致起来, 而且还可能引发语言语法意义模糊、逻辑顺序混乱, 产生“南辕北辙”反相意思的情况。因此, 在英语翻译中必须很好地把握好词类转换技巧。
1.必须将语言表达方式和语体结构特点把握好, 充分认知到“汉语是以含义为主的语言, 而英语是以形式为主的语言”这一特点, 时刻清醒认识到它们均有各自特有的语言形式和语言的表达习惯, 都具有自身独有的语言特点和语言逻辑。
2.必须将两门语言的句式结构把握好, 切忌将句子进行无谓的断句, 从而将所要表达的意思支离破解开来, 最终形成零散意思的“杂乱堆砌”, 导致句式结构的严谨性和章法逻辑思维的缜密性出现问题。
3.必须把握好两门语言语气、风格之间的转换, 特别是相关语法规范、词句的习惯性表达、文化底蕴的差异等方面要重点加以关注, 切实使得翻译出来的内容“忠实”于原文原意;四是必须把握好既通顺又契合语言表达习惯这一原则, 把握好词类转换中的词序与词性变化, 切实正确区分各个词汇之间的关系与作用, 整个语境中把握好翻译技巧, 在不断加强实践中提升英文翻译能力。
三、英语翻译中词类转换方法实践探讨
1.要加强关注名词与动词之间的转换。要认识到在英语句子中, 名词应用相对较多, 而动词的应用则相对较少, 要重点关注一些抽象名词表达动词的用法。比如, “establishment”这词在“The government called for theestablishment of more technical schools”句子中是“名词”, 而将其翻译成中文之后, 进行词类转换, 则可以更加形象地表达该句子的本意。
2.要加强关注介词与动词之间的转换。介词是英语句子中应用较为灵活的词汇, 而且应用较为普遍, 而且在具体意义和涵义表达上具有“动词”倾向, 然而在汉语句子中介词的出现较少, 而且往往导致句子生涩难懂。因此, 加强关注介词与动词之间的转换是搞好英语翻译实践的一个重要关口, 必须对英语中的介词或介词词组给予特别关注, 必须结合具体句子语境实施“具体分析”进行恰当的“动化”, 促使翻译得更加生动与形象, 例如“While she is doing her homework, her feet onthe bench…”这个句子中的“on the bench”, 将其翻译成“腿搁在凳子上”显然更合逻辑性与情理性。
3.要加强关注形容词与动词之间的转换。英语中的形容词常常具有表达某种心理诉求、情感意愿的作用, 因此, 在翻译过程中, 将其“活化”为动词, 常常可以让翻译出来的句子更具生机与活力, 让翻译突显出生命力。例如“If youare often angry, ……”如果将其翻译成形容词, 会得到很生硬, 而将其转换为“动词”, 翻译成“感到生气”, 便明显增添了十足生机与活力。
综上, 英文翻译实践中词性转换较高常见, 对其掌握的情况直接体现出翻译的能力与水平, 必须加强对两门语言结构和词类转换的学习与研究, 加强语境中的情感表达梳理, 科学突破于英文词性的束缚, 全面地理解英语的意义, 正确地实现对词性的转换, 不断加强翻译实践和交流, 从而不断提升英文翻译能力。
参考文献
关键词： 英文翻译 词性转换 使用时机 先兆条件
翻译，简单来说，是将一种语言文字的意义用另一种语言文字表达出来，这一过程是一项有规律可循的行为活动。具体有哪些规律可循，表现为翻译的各类技巧方法。翻译技巧有千千万万种，词性转换是其中较为常见、较为通用和常用的一种技巧。当今社会，翻译的应用领域越来越广泛，但无论是文学翻译、科技论文翻译，还是商业化的翻译，甚至是口译，都在普遍使用词性转换这一技巧。
一、词性转换的意义
英文“translate”的词源意义就是“转换”、“转变”，事实上也隐喻了翻译中最直接最必不可少的一个过程就是转换，从某种意义上讲，可以说无转换则不翻译。翻译中力求的原则就是要忠实于原文，但是两种语言百分之百的忠实翻译并不存在，在翻译活动过程中，主要注重的是使表达意思的正确传达，这个过程中就要舍弃部分对词性的忠实度，这就产生了词性的转换。就像郭著章等在《英汉互译实用教程》中所写的：“在翻译时，由于两种语言在语法习惯表达上的差异，在保证原文意思不变的情况下，译文必须改变词性，这就是词性转译法。”[1]奈达翻译理论同样主张超越词性，利用对原文更深层的理解，使译者避免一些特定情况下的举棋不定。
英文句式的特点是主谓突出，结构分明，其他结构主要以枝叶的形式安插于主干结构之上，但汉语的句式结构相对复杂，不拘泥于某些特定形式，因此在翻译活动过程中，要根据情况灵活转变，不能让原文的词性成为翻译的绊脚石，突破思想，超越词性，才能技高一筹，游刃有余。叶子南认为词性转换“可救译者于‘危难’，一句翻不下去的话，一经转换便起死回生[2]，此言一语道破词性转换的神奇之处。
二、词性转换的类型与实例
词性转换归类可以从原文角度归类，也可以从译文角度归类，从原文角度即分为英语动词、英语名词、英语形容词、英语副词、英语介词等词性转换为其他各类词性。而从译文的角度来讲，则分为各类词性转换为汉语名词、汉语动词、汉语形容词、汉语副词。以下是一些较为典型的实例：
例1名词转动词：It is my conviction that，though men may be no more wicked than they always have been，they seem less likely to be ashamed.（我相信，人们虽然未必比以前还要不讲道德，但似乎要比以前更加不知羞耻。）[3]
名词“conviction”转换为动词“相信”。
例2形容词转动词：I am anxious about my connect flight.（我担心能否赶上转机班机。）
形容词“anxious”转换为动词“担心”。
例3形容词转名词：When we recognize this red-light pattern， we start to see our hidden agendas and realize how challenging it is to accept others as they are. （当我们意识到这种红灯模式时，我们开始看到自己潜在的动机，意识到接受现实中的他人是多么具有挑战性。）[4]
形容词“challenging”转换为名词“挑战性”。
例4动词转名词：These financial titans have over $50 trillion to invest.（这些金融巨头的投资金额超过50万亿美元。）[5]
动词“invest”转换为名词“投资金额”。
例5名词转形容词：The awakeness of our natural communciation system is a thread that runs through every moment of our lives. （清醒的自然沟通系统是贯穿我们生活中每一时刻的中心线。）[4]
名词awakeness转换为形容词“清醒的”。
例6名词转形容词：The water was crystal clear，and as it was only four or five feet deep， he could make all his beginner’s mistakes in perfect safety.（海水晶莹清澈，仅四五英尺深，所以对初学潜泳者来说绝对安全。）[3]
名词“ safety ”翻译成形容词“安全”。
例7副词转形容词：A prolonged example can occur when we’re in a long term with someone who is highly defended and opinionated， unable to accept who we are and what we have to say.（当我们一直在努力沟通，对方却防御心强，很固执，不接受我们，也不接受我们所说的话，这时可能发生长时间的沟通停止。）
副词“highly”转换为形容词。
例8介词转动词：Her efforts go away beyond the call of duty.（她非常努力，大大超出了她的工作职责范围。）
介词“beyond”转换为动词“超出”。
三、词性转换时机的把握及其前提条件
上述例子是一些较为典型的词性转换实例，译者通过对词性转换技巧的灵活运用，较为恰当地实现了翻译的准确、忠实、通顺。因此，准确把握使用词性转换技巧的时机，就成为翻译活动中非常重要的一项技能。
事实上，词性转换的使用并不是没有规律可循的，也不是单单凭借翻译者自身的经验、认识判断使用时机的，更不是通过臆想和灵感来使用的。只要对翻译中该技巧的应用加以总结归纳，就可以得出一些切实可行的使用时机的理论。也就是说，词性转换是存在一些先兆条件的，在出现这些先兆条件的情形下，常常就构成了使用词性转换技巧的时机。
对上文中的实例一一加以分析，即可总结出一些典型的先兆条件。如：
例1前半句为“It is my conviction that”，“it is ... that...”这种句式在译为汉语时，由于其意义较为模糊，因此对my 和 conviction进行词性的转换，使之成为句子的主语和谓语，就比较符合汉语的表达习惯。因此，“it is ... that...”的倒装句和“conviction”一词本身动词意义相当强烈两方面，构成了该情景下使用词性转换的先兆条件。
例2的句式为英文中极为常见的系表结构，这一结构在中文里并没有严格对应的结构句式，且系动词的意义往往并不特别突出。系表结构中当表语的形容词具有较强的动作意味的时候，词性转换就成为了较佳选择。因此，英文的主系表结构和具有强烈动作意味的形容词就构成了该例进行词性转换的条件。
例3中同样出现了“it is ... how...”这样的倒装句式，同时challenging这类词语在翻译中往往加“性”字进行表达更为适宜，译为挑战性。
例4中的have在该句中译为汉语并无合适的对应词语，此时就需要将have所联系的动词转换为名字加以表达，因此此句中意义较为虚弱的have可以视为词性转换的先兆。
例5中“the awakeness of”是典型的the+名词+of修饰名词的结构，该结构就可以作为名词转换为形容词的先兆条件，例6的名词词组的运用也是类似的道理。
例7中的副词“highly”转换为形容词其实最为简单，因为该副词修饰的形容词转化为了名词，所以它随之发生了改变，这种转换的先兆条件最简单明显。
例8中的转换则代表了一类英语中的介词，除句中的“beyond”外，还包括with，in等，这些介词自身的动作意味相当突出，所以在多数情况下，这些介词的出现本身就可以作为词性转换的先兆条件。
综上所述，笔者总结出的词性转换的先兆条件包括几方面：1.英文使用了“it is ... ”来指代的倒装句；2.某词的另一词性意义强烈，如动词的名词意义强烈、形容词的动词意义强烈；3.句中出现have，make等实际意义较为虚弱的词语；4.某词因自身所修饰的词的词性转换而随之转换；5.一些特殊的介词特别适用于进行词性转换。
对上述这些先兆条件的总结和归纳，虽然并不全面和准确，但可以帮助翻译工作者在翻译活动过程中更加熟练地使用词性转换，为翻译工作增强准确性和便捷性。
四、结语
翻译的对等性是相对的，即所谓的“部分对等”，一个待翻译对象的因素包含方方面面，有形式、内容、意义、价值、神韵、词汇、语法、风格、功能、效果等[6]，因此翻译中并不存在完全对等，而是在各种对等中进行取舍，实现相对对等，词性转换就是这种取舍的表现形式之一。原则上来讲，虽然翻译活动不能用条条框框的定律、规律进行完全的概括和照搬，但对某一特定技巧（如本文所阐述的词性转换技巧）加以总结和归纳，对一些先兆条件进行发掘，客观上有利于翻译工作的进行和翻译水平的提高，对于实际的应用具有较为积极的意义。
参考文献：
[1]郭著章，等.英汉互译实用教程[M].武汉大学出版社，2003：58.
[2]叶子南.对翻译中词性转换的新认识[J].中国翻译，2007（6）：52-53.
[3]倪洪源.英汉翻译中的词性转换策略[J].考试周刊，2009（51）：39-40.
[4]靳亚男.浅谈英译汉中的词性转换[D].上海交通大学，2012：39-42.
[5]张倩.财经新闻英译汉词性转换的实践报告[D].大连海事大学，2014：7.
3、输入法不见了:
方法1：
在任务栏单击鼠标右键，弹出快捷菜单，把鼠标移动到“工具栏”上，会弹出子菜单，看看其中的“语言栏”有没有被选中，如果没有选中，单击选中“语言栏”，一般会显示输入法图标。
方法2：
依次单击“开始→设置→控制面板”，打开控制面板，在控制面板中单击“日期、时间、语言和区域设置”，单击“语言和区域设置”，弹出“语言和区域设置”对话框，单击“语言”标签，在“文字服务和输入语言”下单击“详细信息”按钮，弹出“文字服务和输入语言”对话框，单击“高级”标签，在“系统配置”下，把“关闭高级文字服务”前面的对号取消（看到下面的注释了没有，选中“会关闭语言栏”），单击“确定”按钮，输入法图标就回来了。
方法3：
点“开始→运行”，键入“msconfig”，单击“确定”或回车，运行“系统配置实用程序”，在“启动”里把“Ctfmon.exe”选中，单击“确定”，然后注销或重新启动应该就可以了。这是因为Ctfmon.exe控制Alternative User Input Text Processor(TIP)和Microsoft Office语言条，提供语音识别、手写识别、键盘、翻译和其它用户输入技术的支持。这个程序没有启动也会造成输入法图标不显示。
4、XP输入法状态条不见了：
打开注册表编辑器，找到“HKEY_USERS.DEFAULTControl PanelInput
Method”分支，将右边窗口中“Show Status”的键值修改成“1”(“1”为显示状态条，“0”为不显示状态条)，然后重新启动系统，输入法状态条就出来了。此方法对Win 98/2000都适用。
打开“我的电脑→控制面板→区域和语言选项”，在“语言”标签页下的“详细信息”中，点击“设置”标签页下的“语言栏设置”按钮，选择“在桌面显示语言栏”后点击“确定”即可。
From today on, we’ll learn some main translation techniques.For example: Conversion of part of speech;amplification;ommision;how to translate passive voice;how to translate nominal clause;how to translate long sentence;how to translate attributive clause, etc.What we’ll learn today is the first one, that is, Conversion of part of speech.A word in one language belonging to a certain part of speech is not necessarily to be turned into one of the same part of speech in another language.That means it may be translated into another part of speech in another language.For example: a noun, a perposition, an adjective,or an adverbial in one language may be translated into verb in another language;a verb, or an adjective may be translated into noun in another language.As we have learned, English is a noun-dominated language, which means that the noun phase has a high frequency in usage.English sentences tend to be stative.While Chinese is a verb-dominated language.This is because the different way of thinking of the two nations.English speaking people are used to thinking in abstract concepts.Thus English speaking people often express actions through abstract nouns.As these nouns imply some actions, there are hardly corresponding nouns in Chinese to match them.As a result, in translation many such nouns should be better turned into verbs.Therefore, in this chapter we’ll mainly focus on the noun-verb translation.(1)Nouns that imply some action, especially those derived from their corresponding verbs are usually translated into Chinese verbs,(and their attributives naturally become adverbials 见E和H).For examples:
A)The maintenance of the existence of some rare animals has recently claimed world-wide attention.Word-for-word translation of “maintenance of the existence of some rare animals” should be “某些稀有动物生存的保护”.It would sound very awkward.So the noun maintenance here should be translated into verb “保护”.The Chinese version of this sentence should be “保护某些稀有动物的生存，近来已引起了世界范围的广泛关注”。
B)My admiration for him grew more.我对他越来越敬佩
C)The proof of the pudding is in the eating.要想知道布丁的滋味，就要亲自尝一尝。
D)His acceptance of bribes led to his arrest.他因受贿而被捕。
E)The timely arrival of the police stopped the riot.警察及时赶到，制止了骚乱。F)He regretted their failure to reach an agreement.他们未能达成协议，他感到遗憾。
G)He shook his head in feigned disbelief.他故意摇摇头，假装不相信。
H)His continual, unnatural watching of other’s movements aroused our suspicions.他老是鬼鬼祟祟地查看别人的行动，引起了我们的怀疑。
I)His decision could not be indefinitely postponed.他不能无限期地托延下去而 1
不作决定。
J)His exclusion from the tennis club hurt him very much.网球俱乐部拒绝接纳他，这使他很伤心。
K)In the evening after wash and his sit-down tea he went upstairs.晚上，他洗了洗，坐下来喝点茶，然后上楼。
L)Scientists are only beginning to understand why physical workouts can also provide a mental and emotional boost.科学家刚开始了解为什么锻炼身体也能增进智力，改善情绪。
M)The early spring of England is still full of climatic irregularity.英格兰初春的天气常常变幻莫测。
N)How much time would have to pass before he wasn’t her every other thought? 还要过多少时候她才会不再情不自禁地老想起他呢？
We can find that the logical subject(agent of action)of this type of noun is often a possessive case.However, the possessive may not always refer to the logical subject but sometimes to the logical object(patient of the action).For example:
More troops have been sent to your protection.已派更多的部队来保护你们。
(2)Nouns appearing in the “there be…” pattern and similar pattern showing existence can also be translated into Chinese verbs.For examples:
A)There was a sudden fall in temperature.气温突然下降。
B)There has been an outbreak of SARS in this community.这个小区爆发了非典。
C)There is a powerful social argument for a firmer standard of spoken English.社会上有许多人大力主张英语口语应该有一个严格的标准。
D)In such a case it is impossible for there to be any escape from exposure.在这种情况下，谁也不可能躲开不被暴露。
E)There were only sporadic attempts to answer such questions.只有零零星星几个人试着回答这样的问题。
(3)Nouns of –er form sometimes don’t have corresponding words in chinese.A proper way to transiate them is to turn then into verbs, and sure, their attributive modifiers are better turned into adverbials.A)he is a heavy smoker.他抽烟很厉害。
B)he is a good listerner and they like to talk with him.他能倾听别人意见，因此他们喜欢和他聊天。
C)he is considered as a poor loser.人们认为他输不起。
D)what’s the matter? You’re all clock-watchers today.你们今天一直不停看钟，是怎么回事呀？
Native English speakers seem to prefer to use this kind of noun to describe a person, bur we chinese tend to use verbs.For examole, we often say 他学习很用功。However, in English, “he is a good student” is preferable to “he studies hard”.Therefore, we should adopt this pattern in C-E translation.For example: 她衣着时
髦。She is a sharp dresser；she is a fashionable dresser
(4)Apart from such “dynamic nouns”, which means nouns imply actions, very often some other nouns can also be turned into verbs, or with verbs added in English-Chinese translation in order to make more smooth and natural translation.For examples:
A)But reality makes things difficult.但是一接触现实，事情就难办了。
B)She considered housework demeaning and the care of children an added insult.她认为干家务活低人一等，带孩子更丢人。
C)After more than two centuries of wind and rain, the doors and windows were mouldering.经历了两百多年的风吹雨打，门窗都朽坏了。
D)Example is not the main thing in influencing.It is the only thing.以身作则不但是影响人的主要方法，而是唯一的方法。
E)She went and tapped at Liddy’s door, and after some labor awoke her.她敲了敲丽蒂的门，颇费了周折才把她叫醒。
F)To some extent it gets into the question of the chicken or the egg.在某种程度上说，这已成了先有鸡还是先有蛋的问题。
G)Your arm looks like a hospital job.Are you all right? 看上去你的胳膊好像动过手术。你有什么不舒服吗？
H)I’m a sight in the early morning—I admit it.我承认，我大清早这样做有点招摇过市。
I)Such actions would become good headlines tomorrow.如果采取这样的行动，一定会成为明天报纸的头条新闻。
J)The short cut would take us five hours to get there.(就是)抄近路我们（也要）五个小时才能到那里。
(5)nouns in some special idiomatic usage, such as “all +noun”、“have +a noun”, are always turned into verbs.A)the girl was all smiles.姑娘笑逐颜开。
B)he is all eyes 她全神贯注地看着
C)life is by no means all pleasure 生活不仅仅是享乐
D)they took a final look at Iron Mike，still intact in the darkness 他们最后看了一眼铁麦克一眼——它依旧安然无恙地耸立在黑暗之中。
(5)nouns fernquently appear in English posters.Their counterparts in Chinese often use verbs.A)No parking.禁止停车。
B)No photographing.禁止摄影。
C)No admittance except on business.闲人免进。
D)Under construction.正在施工。
E)No money down.免付定金。
F)No hawkers.不准在此设摊兜售。
G)Satisfaction or your money back.包您满意，不满退款。
H)A drink on the house.本店免费提供饮料。
1.介词转译成动词。（prep.---v.）
(1)
(2)
(3)It is our goal that the people in the undeveloped areas will be finally poverty.(4)
2.形容词转译成动词（adj.---v.）
(1)Integrity means you do what you do because it’s right错。
(2)Don’t be might have a better idea or who might even be smarter than you are.(3)
3.副词转译为动词（adv.---v.）
(1)
(2)
(3)
1汉语动词的转换
汉语动词的使用频率远远高于英语。这是因为按照英语句法，受主谓关系的限制，一个 简单句或分句大多只有一个谓语动词。而且，英语还可以通过谓语动词以外各种词性的词来体现动词意义。因此将汉语句子里的动词转换为英语里其他词性的词是翻译中的常用技巧之一。
例1 这本书反映了30年代的中国社会。
译文:The book is a reflection of Chinese society in the 1930s.(将汉语动词转换为英语名词)
例2 他们不满足于现有的成就。
译文:They were not content with their present achievements.(将汉语动词转换为英语形容词)
例3 我想男孩与女孩的思维方式不同。
译文:I suppose boys think differently from girls.(将汉语动词转换为英语副词)
例4 你赞成还是反对这项计划?
译文:Are you for or against the plan?(将汉语动词转化为英语介词) 2.汉语名词的转换
英语中有很多由名词派生的动词，以及由名词转用的副词，形容词等。在汉译英时，汉 语中的名词常常可以产生一些转换，从而更简洁有力地表达原文。
例5 他们尽了最大的努力帮助病号和伤员。
译文:They did their best to help the sick and the wounded.(汉语名词转换为英语副词)
例6 钢的含炭量越高，强度和硬度就越大。
译文:The more carbon the steel contains, the harder and stronger it is.(汉语名词转换为英语形容词表示特征和性质)
例7 这就是你不对的地方。
译文:This is where you are wrong.(汉语名词转换为英语副词)
例8 我的体重比过去轻了。
译文:I weigh less than I used to.(汉语名词转换为英语动词) 3.汉语形容词的转换 在汉译英时，汉语的形容词往往可以译成英语中的名词或副词。这些名词或副词通常具 有抽象意义，而且往往由某些形容词派生而来。
例9 我们感到，解决这个复杂的问题是困难的。
译文:We found difficulty in solving this complicated problem.(汉语形容词转换为英语名词)
例10 有时候我们不得不为错误付出昂贵的代价。
译文:Sometimes we have to pay dearly for mistakes.(汉语形容词转换为英语副词) 4.汉语副词的转换
有时出于修辞和句法结构的需要，往往把汉语中的副词用英语其他词性的词来表达，这也是翻译中的一个常用技巧。
例11 独立思考对学习是绝对必需的。
