as与as的用法小结（精选7篇）
一、用作介词，as与like用法区别
[例1] Let’s learn to use the problem we are facing ______ a stepping-stone to future success.(NMET 2008全国卷)A.to B.for C.as D.by [解析] C。as作介词表“作为”，常接在treat/regard/recognize/use等动词之后；而like表“像„„一样”。试比较：
(1)He is a child, and must be treated as such.他年幼，应该当孩子对待。(2)He acted like a child, while he had grown up.他虽已成人，但做事却像孩子一样。
二、用作从属连词
1．表时间，as/when/while用法区别
[例2] Mother was worried because little Alice was ill, especially ______ Father was away in France.(NMET 1994全国卷)A.as B.that C.during D.if [解析] A。主从句动作先后发生常用when；两个较长动作同时发生用while；特别强调主从句动作同时发生用as，译作“一边„„一边”，as还可表“随着”。另when, while还可用作并列连词。when表at that time，而while表“两相对照”。
2．表原因，as/because/since/for用法区别
[例3] Jenny was very sad over the loss of the photos she had shot at Canada, ______ this was a memory she especially treasured.(NMET 2006广东卷)A.as B.if C.when D.where [解析]A。as 作从属连词引导原因状语从句。as和because, since, for的区别是：because语势最强，用来说明人所未知的原因，回答why提出的问题，可置于强调句中且其前可加修饰语； since是双方都知晓原因或经过分析而得之的原因，语气次之；for是并列连词，前用逗号隔开，表逻辑推理或补充说明；as语气最弱，原因是显而易见的或已为人们所知，即已知原因，所引导的分句可置于句首。
3．表转折，引导让步状语从句[来源:学科网ZXXK]
[例4] ______, he talks a lot about his favorite singers after class.(NMET 2005重庆卷）
A.A quiet student as he may be B.Quiet student as he may be C.Be a quiet student as he may D.Quiet as he may be a student [解析] B。as 引导让步状语从句时，形容词、副词、动词等常置前；若表语为名词，前置时使用零冠词；从句谓语动词常和助动词或情态动词may, might, will, would等连用。
4．表正如，引导方式状语从句
[例5] —Who should be responsible for the accident? —The boss, not the workers.They just carried out the order ______.(NMET 2008福建卷)A.as told B.as are told C.as telling D.as they told [解析]A。as引导方式状语从句，表按照、正如；非限定分句“从属连词+-ed/-ing形式” 可以看作是一种省略，即省略了主语和be动词。究竟使用何种非谓语动词形式取决于主被动关系。又如：
(1)As I explained on the phone, your request will be considered at the next meeting.（NMET 2005浙江卷）
(2)Doctors have said that as many as 40 percent of patients don’t take medicine as directed.三、用作关系代词，指代整个句子，as/which/it用法区别
[例6] The Beatles, ______ many of you are old enough to remember, came from Liverpool.(NMET 2006天津卷)A.what B.that C.how D.as [解析] D。as作关系代词，在非限制性定语从句中，可指代整个句子内容，置于句首，而which不可；it为代词，用作句子成分，但不用来连接句子，故常和并列连词连用；在限制性定语从句中常与such, the same连用，试比较：[来源:Zxxk.Com]
(1)I haven’t many toys but I will send you such as I have.我的玩具并不多。不过，我会把我仅有的一点玩具送给你。
(2)The book is not such that I can advise you to read it.这本书并不怎么样，我没法向你推介。
四、用作从句性替代词，等同于so
[例7] —My room gets very cold at night.—______.(NMET 2007江苏卷)A.So is mine B.So mine is C.So does mine D.So mine does [解析]C。从题干中动词gets得知，助动词应选择do的适当形式，故排除选项A和B；从语序上考虑，排除选项D。as用作从句性替代词，等同于so，只是用于正式语体中。如：Our eating habits have changed, as has our way of life.五、as„as结构
1．构成倍数比较句型：n times+as„as
[例8] What a table!I’ ve never seen such a thing before.It is ______ it is long.（NMET 2005湖北卷）
A.half not as wide as B.wide not as half as C.not half as wide as D.as wide as not half [解析]答案C。not与谓语动词连用构成否定。as 作从属连词引导比较状语从句，常见结构为as...as，第一个as为副词，后接形容词或副词，第二个as为连词。程度修饰语应放在第一个as之前。
2.as/so long as
[例9] —Have you got any idea for the summer vacation?[来源:学&科&网] —I don’t mind where we go ______ there’s sun, sea and beach.(NMET 2008全国卷)A.as if B.as long as C.now that D.in order that [解析] B。as long as最基本词义表示主从句动作延续时间一样长，可引导时间状语从句；若引导条件状语从句，表“只要”，同only if，为唯一条件。又如：
As long as I know the money is safe, I shall not worry about it.（NMET 2003北京卷）
3.as far as
[例10] ______ I can see, there is only one possible way to keep away from the danger.（NMET 2004北京春季卷）
A.As long as B.As far as C.Just as D.Even if [解析] B。as far as I knowcan seeam concerned表据我所知（我看、我所关心的）；as far as还表“远至”。
4.as much as
[例11] The more I think about him, the more reasons I find for loving him ______ I did.（NMET 2005湖南卷）
A.as much as B.as long as C.as soon as D.as far as [解析]A。as much as表程度或数量；as long as表长度或条件；as soon as尽快；as far as远至，根据。若用于否定句中，第一个as换为so。例：Young people in the US don’t care so much about fashion as those in China.5.as well as
[例12] John plays football ______, David.(NMET 1994全国卷)A.as well B.as well as C.so well D.so well as [解析]B。if not better than为插入语，对考生答题具有一定干扰。as well as在功能上相当于并列连词，用来连接两个平行成分，但不能用作并列连词。注意在连接两个并列谓语动词时，其后的动词使用动词-ing形式；除此之外，所连接的成分前后应保持平行、对等。试比较：
⑴ Computers have been put into robots and _____to make mobile phones as well as _______with medical operations.(原创模拟)A.used;to help B.used;help C.using;helping D.using;helped ⑵ Computers have been put into robots as well as _____to make mobile phones and _______with medical operations.(原创模拟)[来源:Zxxk.Com]
A.used;to help B.having been used;help C.being used;helping D.using;helped 答案与解析：⑴B；⑵B。⑴中and为并列连词，used与谓语动词put保持一致。as well as用来连接两个并列状语，作不定式的宾语，故make与help保持一致；⑵中as well as用来连接两个并列动词，故紧随其后的动词使用-ing形式，并与谓语动词照应，使用having been used形式。其后and为并列连词，连接并列状语，作不定式的宾语，保持一致。
6.as good as
[例13] He said he would do whatever he could to help me, and he was ______ his word.A.as good as B.as well as C.as much as D.as many as [解析]A。as good as最基本词义是“和„„一样好”；还可表示“几乎，简直是”，其后接名词、动词或形容词均可，在功能上相当于副词very nearly。如：
⑴The work is as good as finished.工作基本完成。
⑵If he finds out, I’m as good as dead.要是他发现了，我就完了。
六、as其他常见搭配 1．so as to
[例14] All these gifts must be mailed immediately ______ in time for Christmas.（NMET 2005辽宁卷）
A.in order to have received B.in order to receive C.so as to be received D.so as to be receiving [解析] C。so+(adj./adv.)as to do既表目的又可表结果，在表目的时可以和in order to换用但不可置于句首。so后接形容词或副词时只表结果。此题结合时态和语态对考生进行综合考查。试比较：
[例15] My English teacher’s humor was ______ make every student burst into laughter.(NMET 2008江西卷)A.so as to B.such as to C.such that D.so that [解析]B。从题干动词make可以看出，选项C和D应排除，sosuch that为从属连词，后接从句；此处such 为代词，表这样的人或物，作表语，后续不定式表
结果，其前加as to以示强调。试比较：My English teacher’s humor was such that makes every student burst into laughter.[来源:学科网ZXXK][来源:Z_xx_k.Com] 2．as against/for/to/with
[例16] ______ pandas, golden monkeys are in danger of dying out in our country.A.As against B.As for C.As to D.As with [解析] D。此题考查as的常见搭配。as against与„„相对；as for somebodysomething就„„而言；as to(依照一定的标准或原则)根据、依照；as with和„„一样。
3.as if/though
[例17] Elize remembers everything exactly as if it ______ yesterday.(NMET 2006全国卷)A.was happening B.happens C.has happened D.happened [解析]D。as if 引导方式状语从句，同时涉及虚拟语气的用法。主从句动作同时发生，对现在假设，从句用一般过去时；若对过去假设则用过去完成时。as if后还可接to dodoing等。如：He opens his mouth as if to speak.他张开嘴好像要说话。
4.as还有以下常见搭配：
(1)Leave the book as it was.把书原样放好。
(2)Just as exercise is to the body, so is reading to the mind.正如锻炼对身体很重要，读书对大脑也一样重要。
(3)My friend Martin was very sick with a strange fever;as a result, he could neither eat nor sleep.我的朋友马丁患了一种奇怪的感冒。结果，病折腾得他既不能吃又不能睡。
(4)Steve, as usual, was the last to arrive.史蒂夫照例来得最晚。(5)Wild flowers such as orchids and primroses are becoming rare.兰花、报春花等野花越来越稀少。[来源:Zxxk.Com] 巩固性练习：
1.There at the door stood a girl about the same height ______.A.as me B.as mine C.with mine D.with me 2.______ production up by 60%, the company has had another excellent year.A.As B.For C.With D.Through 3.______ the day went on, the weather got worse.A.With B.Since C.While D.As 4.I do every single bit of house work ______ my husband Bob just does the dishes now and then.A.since B.while C.when D.as5 5.We had better hurry ______ it is getting dark.A.and B.but C.as D.unless 6.We cannot figure out ______ quite a number of insects, birds, and animals are dying out.A.that B.as C.why D.when 7.Parents should take seriously their children’s requests for sunglasses ______ eye protection is necessary in sunny weather.A.because B.though C.unless D.if 8.______ everybody knows about it, I don’t want to talk any more.A.For B.Even C.Since D.However 9.______, he doesn’t study well.A.As he is clever B.He is as clever C.Clever as he is D.As clever he is 10.Famous as he is, ______.A.his works are not widely read B.but his works are not widely read C.however his works are not widely read D.still his works are not widely read 11.______, I have never seen anyone who’s as capable as John.A.As long as I have traveled B.Now that I have traveled so much C.Much as I have traveled D.As I have traveled so much 12.______ is reported in the newspapers, talks between the two countries are making progress.A.It B.As C.That D.What 13.______ is often the case, we have worked out the production plan.A.Which B.When C.What D.As[来源:学科网ZXXK] 14.—It’s burning hot today, isn’t it? —Yes.______ yesterday.A.As was it B.So it was C.As it is D.So is it 15.It is reported that the United States uses ______ energy as the whole of Europe.A.as twice B.twice much C.twice much as D.twice as much 16.Our neighbor has ______ours.A.as a big house as B.as big a house as C.the same big house as D.a house the same big as[来源:学,科,网Z,X,X,K] 17.Americans eat ______ vegetables per person today as they did in 1910.A.more than twice B.as twice as many
C.twice as many as D.more than twice as many 18.The WTO cannot live up to its name ______ it does not include a country that is home to one fifth of mankind.A.as long as B.while C.if D.even though 19.After supper she would sit down by the fire, sometimes for ______ an hour, thinking of her young and happy days.A.as long as B.as soon as C.as much as D.as many as 20.—How far apart do they live? —______ I know, they live in the same neighborhood.A.As long as B.As far as C.As well as D.As often as 21.When a pencil is partly in a glass of water, it looks as if it ______.A.breaks B.has broken C.were broken D.had been broken 22.John shut everybody out of the kitchen ______ he could prepare his grand surprise for the party.[来源:学科网] A.which B.when C.so that D.as if 23.The man we followed suddenly stopped and looked as if ______ whether he was going in the right direction.A.seeing B.having seen C.to have seen D.to see 24.Tom kept quiet about the accident ______ lose his job.A.so not as to B.so as not to C.so as to not D.not so as to 25.A typhoon swept across tiffs area with heavy rains and winds ______ strong as 113 miles per hour.A.too B.very C.so D.as
26.The organization encourages members to meet on a regular basis, ______ them with financial support.A.as well as providing B.as much as provide C.as good as providing D.as far as provide 27.We’re going to the cinema tonight, why don’t you come along _____? A.though B.yet C.however D.as well 28.They own a house in the city ________a villa in the countryside.A.as many as B.as much as C.as good as D.as well as 29.____is our belief that improvements in health care will lead to a stronger, more prosperous economy.A.As B.That C.This D.Such 30.Pop music is such an important part of society _____ has even influenced our language.A.as B.that C.which D.where 参考答案：1~5 BCDBC 6~10 CACCA 11~15 CBDAD 16~20 BDCAB 21~25 CCDBD 部分难题答案与解析：
1.B 搭配the same „as„，mine同my height。
16.B as„as结构中第一个as为副词，后续形容词或副词。选项C应变为the same house as big as；选项D应改为a house as big as。
29.D such表这样的人或物，构成“Such is+主语”结构，our belief后续从句为同位语从句。
1) This elephant is like a snake, as anybody can see.谁都看得出来, 这头大象就像一条蛇。
2) The stems of bamboo are hollow, which make them very light.竹子的躯干是空心的, 所以很轻。
在上面的两个句子中, as与which的用法极其相似, 它们分别引导一个以整个句子为先行内容的非限制性定语从句。那么as与which在引导这类非限制性定语从句时, 其用法是否完全相同呢?下面从三个方面阐述。
1 as与which词义比较
which引导这类定语从句时, 词义相当明确, 常可译成“这一点、这件事”.as却较特殊, 虽然一些词典也把它解释为and this (这一点, 这件事) , 但我们认为, 仅仅这样解释有可能导致下面句子的转换错误:
3) He saw the girl, and this delighted him.他看到了那姑娘, 这使他很高兴。
He saw the girl, which delighted him.
He saw the girl, as delighted him.
As用作这一特殊关系代词时, 与它在状语从句中所起的作用有着相当密切的关系, 在引导这类非限定性定语从句时, 具有两重性, 即在结构上它象which一样是一个关系代词, 而在语义上它仍然相当于一个表示“如, 正如”含义的一般连词。
2 as与which句法比较
as与which在句法上都有各自的一些习惯用法, 不能混淆, 下面作一简单归纳。
2.1 which常常用作实意动词的主语, 这时它所引导的从句与主句之间常常含有并列因果等关系
4) They moved the fallen tree, which took a long time.
他们把倒下的树搬走了, 这费了不少时间。
5) We took a short cut through the woods, which saved about ten minutes.
我们抄近路穿过树林, 这使我们少花了大约十分钟。以上两句相当于一个由and连接的并列句。
6) The child had fever every night, which worried his parents very much.
这孩子每晚发烧, 这使他父母非常焦急。
7) She mimicked everything he said, which made him furious.
她模仿他说话, 这使他勃然大怒。
以上两句多少含有某种逻辑上的因果关系, 从句中的谓语动词常用make, worry, delay, upset, enrage, annoy.等“使役动词”。
在以上四个句子中, as是绝对不能用的。
2.2 as常作一些实义动词的宾语, 这类动词与as几乎成了一种固定搭配
8) He is tired, as anybody can see.
他累了, 这一点大家都能看得出来。
9) As we know now, heavy objects and light objects fall at the same speed unless air holds them back..
我们现在都知道, 如果没有空气的阻力, 重的物体和轻的物体下落的速度是一样的。
10) There was, as I remember, a bar around here.我记得这儿附近有一家酒吧。
这时一般用as, 偶尔也有用which的, 例如:
11) Moreover, which you may hardly believe, the examiners had decided in advance to fail half the candidates!
此外, 你可能很难相信, 主考人员事先已经决定要淘汰一半应考人!
这里的which用的比较别扭, 但是当从句的谓语动词是否定形式或从句谓语带的是一个复合宾语结构时, 一般只能用which, 例如:
12) One has to eat standing up in that bar, which I don‘like.在那家酒吧得站着吃东西, 这我可不喜欢。
13) You pretended not to know me, which I didn‘t understand.你假装不认识我, 这我可弄不明白为什么。
14) He admires Mrs.Brown, which I find strange.他很爱慕布朗夫人, 这使我觉得很奇怪。
2.3 当从句谓语是由系动词+形容词构成时, 常用which作主语
15) He married her, which was disgraceful.他同她结了婚, 这很不光彩。
16) She cycled from London to Glasgow, which is pretty good for a woman of 75.她骑自行车从伦敦到格拉斯哥, 这对一位七十五岁的妇女来说真是不简单。
17) They have invited me to dinner, which is very kind of them.他们请我去吃饭, 这真是太客气了。
As只能与少数几个形容词连用, 如clear, evident等, 例如:
18) He is a foreigner, as is clear from his appearance.他是个外国人, 这一点可以从他的外表清楚地看出来。
19) The caller was an old lady, as was evident from the voice on the phone.打电话的是一位老妇人, 这从电话的声音可以明显地听出来。
不难发现, as与which这时有明显不同。用which时, 主句先是陈述一桩事情, 然后从句补充说话人对主句所表示内容的看法。用as时, 主句是说话人作出的判断, 从句则提供一种理由或依据。在结构上, which引导的这类定语从句中的形容词有不少具有这类性质, 即都可以带一个不定式的复合结构。比如下面三个句子在语法上同样是成立的:
20) It was disgraceful of him to have married her.
21) It is pretty good for a woman of 75 to cycle from London to Glasgow.
22) It is very kind of them to have invited me to dinner.
而as引导的从句中的形容词却不具有这种特性, 不能带不定式复合结构, 但可以带that从句, 比如句18、19可以说成:
23) It is clear from his appearance that he is a foreigner.
24) It was evident from the voice on the phone that the caller was an old lady.
注意:有些形容词几乎与as组成了固定搭配, 如as is most likely, as is well known, as is natural.等等。
2.4 用简洁表达法, 而且两种句子意思不尽相同, as引导的这类定语从句意义上更像一个状语从句。
试比较:
25) He died of cancer, which is what I predicted.他死于癌症, 这正是我所预料的。
26) He died of cancer, as I predicted.正如我所预料的那样, 他死于癌症。
27) The activity was postponed, which was exactly what we wanted.这项活动延期了, 这正是我们所希望的。
28) The activity was postponed, as we exactly wanted.正如我们所希望的那样, 这项活动延期了。
29) Caroline was elected by a large majority, which was what most people had expected.卡罗琳以多数票当选, 这正是大多数人所期望的。
30) Caroline was elected by a large majority, as most people had expected.正如大多数人所期望的那样, 卡罗琳以多数票当选了。
用which结构时, 句子意思侧重表示主句所陈述的事实同猜想、预期的情况相符;用as结构时, 句子意思侧重表示猜想预料的情况已经变成或将变成事实。这时, 虽说as引导的从句在意义上更像状语从句, 但在句法结构上仍不失为一个非限制性定语从句, 因为, 这时的as从句与as引导的一般状语从句还是有着明显区别的。试比较下面两个句子:
31) He died of cancer, as his father had done.
在前一个句子里, as用作特殊关系代词, 代替主句所表示的内容, 在它所引导的非限定性定语从句中作predict的定语。在后一个句子里, as是一般连词, 意思是in the same way that, 它引导的是一个方式状语从句, 全句的意思是:他像父亲一样死于癌症。
2.5 as常接report, announce, say, expect等动词的被动语态
例如:
32) He opposed the idea, as could be expected.正如可以预料的那样, 他反对这个意见。
33) As has been said above, grammar is not a set of dead rules.正如前面所述, 语法并不是一套死规则。
34) A new hotel will be built, as is announced in today‘s papers.据今天报载, 将建造一家新旅馆。
2.6 which本身在从句中还可用作定语、介词宾语, 而as却不能
35) He is very old, which fact is important.他年纪很大了, 这个事实相当重要。
36) He may come, in which case I‘ll ask him.他可能会来的, 要是那样的话我就去问他。
37) He changed his mind for the second time, after which I refused ever to go out with him again.他再一次改变了主意, 之后, 我拒绝再和他一块出去了。
3 as从句与which从句在句子中的位置
as从句与which从句在句子中的位置问题一般并无争议。Which从句一般位于主句之后, 不能放在主句前面, 不能说:
38) Which was reckless, Jack drove too fast.
而只能说:
38) Jack drove too fast, which was reckless.
杰克开车太快了, 这简直有点胡来。
As从句的位置则比较灵活, 一般可以放在句首、句中、或句末, 例如:
39) As was expected, he performed the task with success.正如预料的那样, 他成功地完成了那项任务。
40) The Smiths, as you probably know, are going to America.你们可能知道, 史密斯全家打算去美国。
综上所述, which引导的这类非限定性定语从句无论是在结构上还是在意义上都是无容置疑的。而as引导的这类非限定性定语从句往往只是在结构上较为明显, 在意义上多少有点像状语从句, 有的语法学家把它称之为“状语化的定语从句”。as从句在句子中的位置的灵活性正好证明了这一观点。当然, as与某些单词、结构的搭配能力相当强, 而且比较固定, 也就是说具有某种习语特性。正是由于这些原因, 我们认为as与which在使用时应当特别慎重, 一般不宜随便替换。以上笔者只是简单作了些归纳、比较, 谈了一些粗浅的看法, 不当之处还望同行加以批评指正。
摘要：as与which用法比较、从词义句法和它们引导的从句在句子中的位置来加以说明比较, 牢固掌握灵活运用。
关键词：as与which用法,比较,词义,句法,位置
参考文献
【关键词】as well as 用法 例句
as well as 有多种用法，现归纳并说明如下，
一、作并列连词，用以连接前后两个语法单位和功能一致的词语，形成A as well as B的结构，说话人意在强调A， 故A和B的位置不可互换，但汉译时应先译B，后译A，可译为“不但……而且……”或“既……又……“等。可被连接的词语有：
1.名词或代词，例：
（1）The students as well as the teacher swim every day. （比较：Not only teacher but also the students swim every day.） 不但老师，而且学生也每天游泳。
（2）He as well as you is responsible. （Not only you but also he is responsible）.不仅你而且他也有责任。
注：1）.A as well as B 结构作主语时，谓语动词的人称和数应与A 一致； 2）. A as well as B 结构作主语时， 可把A 保留在主语位置，而将 as well as B 加逗号于其前移置句末，如例2可改为：He is responsible， as well as you.
2.形容词或副词，例：The packing must be seaworthy as well as strong enough to stand shock and rough handling. 包装得坚固经得起震动和粗暴搬运，而且得适于海运。
3.介词结构，例：We traveled by night as well as by day. 我们日夜兼程。
4.谓语动词或非谓语动词。在此种情况下，前后两个谓语动词必须保持时态一致。在两个不定式中，后一个不定式的to可保留也可省去。
He publishes as well as prints his own books.他印刷且出版他自己的书。
二、依然用作并列连词并形成as well as B结构，但说话人对A 和B 均无强调倾向，as well as B只是表示增补或引伸，汉译按照原句顺序，A和B的位置不必颠倒，可译为“和”或“以及”等，连接的词语与第一种用法相同。例：Air as well as water is needed to make plants grow.空气和水是植物生长所必须的。
三、用作介词，常用于as well as doing…的结构中，可译为“除了……还……”也可译为“ 不但……而且……”等；as well as doing可位于句末，也可位于句首，但必须分别在前后加上逗号，例：The Japanese devils slaughtered the villagers， as well as burning down their houses. （= As well as burning down their houses， the Japanese devils slaughtered the villagers. 日本鬼子不仅烧毁了村民的房子，还屠杀了村民。
四、和 not only…but also…不同，as well as 可用于否定句，分两种情况：（1）as well as 位于not前，所连接的两部分均否定；（2）位于 not 后， 否定前者，肯定后者，as well as可译为“ 和……一样”等，例：Mr. Wang as well as Mr. Li does not teach history. （= Neither Mr. Wang nor Mr. Li teaches history.）王先生和李先生一样都不教历史。
比较：Mr. Wang does not teach history， as well as Mr. Li. 王先生不象李先生一样教历史。
A. much as an art as B. as much an art as C.an art as much as D.as much as an art
2. _____ I admire David as a poet,I don’t like him as a man.
A.Only if B.If only C. As much D.Much as
3. ____ ,he talks a lot about his favourite singers after class.
A.A quiet student as he may be B.Quiet student as he may be
C.Quiet as he may be a student D.As he may be a quiet student
4.I wonder why you don’t do it as ____ and it’s the third time you have done so.
A.told you B. be told C. told to D. you told
5.( 1) ___I explain on the phone,your request will be considered at the next meeting.
(2)____ I explain on the phone is that your request will be considered at the next meeting.
A. What B.When C.After D. As
6.(1)That is ____ problem____can’t be worked out by anyof us .
(2)That is ____problem____none of us can work it out.
A.a such difficult , that B.so difficult a ,that
C.such a difficult, as D.a so difficult ,as
7.There were not so many jobs available ____ were asked for.
A. that B. which C. what D. as
8.____ time went on,Einstine’theory_____ right.
A. With, proved B As, be proved C.With, be proved D. As, proved
1such as用法：在后面的`分句中，对前面的分句加以解释，说明原因，两个分句间用逗号隔开，后面分句比较强调。such常与as连用，用于列举事物，意为“例如，像…一样”，其后所述数量也不可全部列出。such as在同一句中也可分开配合使用，此时as在从句中用作主语或宾语。
2.like用法：like是表示感觉的动词，不能用于进行体中，也不用于现在完成时，一般不用于被动结构。动词不定式充当补足语的复合宾语，作“想要”解时，用作like的宾语的动名词可用属格或者宾格的代词，表示其逻辑主体。
侧重点不同
1.such as侧重点：侧重于强调列举出来的东西。
随着AS5643协议在航空领域应用日益广泛, 在进行研发、测试和故障检测时需要一种可以对总线进行监控的设备以完成对实际传输数据的分析, 从而为研发和测试提供依据。现提出了一种基于AS5643协议总线分析仪的设计思路, 用于完成对基于AS5643协议的通信网络进行实时通信数据的采集和监控, 完成AS5643数据包的发送、实时状态监控、数据包记录和解析及总线拓扑结构显示等诸多功能, 从工作原理、硬件及软件设计的重点环节进行了阐述, 并通过实验仿真平台对分析仪的性能进行了验证。
1 总线分析仪工作原理
基于AS5643协议的总线分析仪体系结构如图1所示。总线分析仪实现单节点总线上的1394设备节点通过PHY和LINK芯片完成与数据与FPGA交互, 总线分析仪使用FPGA作为主控制器, 完成对板卡上数据的处理;使用1394线缆与总线上的节点相连, 通过USB接口和PC机进行通信, 采用两片SDRAM作为数据缓冲区, 并使用1394链路层芯片和物理层芯片完成对通过1394物理层和链路层数据的处理。
接收数据包的工作原理为:1394网络节点发送AS5643数据包经过线缆传送至总线分析仪的某个端口, 经过1394物理层芯片和链路层芯片处理后与主控芯片FPGA进行数据交互。由于数据的传输量大、传输速率快, 故使用两片SDRAM作为数据缓冲区来暂存捕获到的数据。当上层应用程序发出接收数据的请求, FPGA将数据包添加时标、状态信息字后封装成USB包写入USB芯片的FIFO。上层应用程序通过USB驱动程序将数据从USB FIFO读入到上位机内存, 按照AS5643数据包的格式进行解析, 将相关字段显示在界面上。
发送数据包的工作原理为:上层应用软件根据用户输入的通道号、消息负载、事务代码等信息, 通过驱动程序写入USB的FIFO中, 由FPGA将其封装成AS5643数据包, 在规定的时间内通过1394链路层和物理层芯片将数据包发送到网络上。
FPGA可以采用USB芯片支持的四种方式将数据上传至上位机内存:控制传输、批量传输、中断传输、等时传输[3]。控制 (Control) 传输主要用于外设与主机之间的控制、状态、配置等信息的传输, 为外设与主机提供控制通道;批量 (Bulk) 传输的数据是连续的, 支持大量的数据传输;中断 (Interrupt) 传输的数据是少量的, 且其数据延迟时间范围有限;而同步 (Isochronous) 传输一般用于周期性、有限的时延和带宽且数据传输速率不变的外设与主机间的数据传输。对于本系统的应用, 需要满足两点要求: (1) 数据传输必须正确可靠, 即保证数据传输的无损性; (2) 数据传输的实时性, 即能保证不丢失数据包。鉴于上述两点考虑, 总线分析仪采用批量传输方式。
2 总线分析仪的实现
2.1 硬件设计
总线分析仪的硬件由FPGA模块、USB接口模块、SDRAM存储模块、1394链路层芯片和1394PHY组成。系统的核心采用FPGA专用集成电路用于控制外部PHY芯片、LINK芯片、SDRAM以及与USB2.0 (CY7C68013) 芯片的通信和数据交互。USB芯片外围引脚电路图如图2所示。
FPGA实现的主要功能如下: (1) 采集来自三个链路Link中的信号, 将其存储在外部SDRAM芯片中; (2) 将SDRAM芯片中的数据读出, 并写入USB芯片相应的FIFO中; (3) 解析来自USB芯片的消息, 实现PC机对FPGA内部的控制。
FPGA内部重要组成模块如图3所示, 各模块功能如下。
2.1.1 LINK
用于接收来自链路的数据包, 并且在存储管理模块的控制下, 公平有序地写入SDRAM存储器。链路层支持100 Mb·s-1/200 Mb·s-1/400 Mb·s-1的链路速度, 支持最大帧长的配置和CRC检查, 为监控帧提供完整的错误状态信息。1394总线分析仪中的三路LINK完全独立, 可以同时采集3个链路上的数据进行监控。采集到的数据帧被暂时写入接收FIFO, 等待最终被写入SDRAM存储器。
2.1.2 时标计时器
时标计时器是一个32位的实时时间计数器, 用于为监控帧提供接收时标, 计时精度为1μs。由于USB芯片接口的数据位宽为16位, 因此在提供时标时, 先提供高16位的计时值, 再提供低16位的计时值。时标计时器时上电复位后初始值为0, 不主动计数。在监控触发模式下, 只有主机开启数据监控, 时标计时器才会计数;当停止监控时, 时标计时器的值被复位为0。在接收帧触发模式下 (监控必须开启, 否则仍不计数) , 当任何打开的监控端口接收到第一帧数据时, 启动时标计时器;当停止监控时, 时标计时器的值被复位为0。
2.1.3 SDRAM控制器
用于控制SDRAM存储器的读写操作;SDRAM控制器是FPGA内部与外部SDRAM存储器之间的接口。FPGA内部有两个独立的SDRAM控制器, 每个控制器最大支持512MB的片选空间, 片选空间的起始地址与结束地址可编程, SDRAM逻辑BANK数可编程, 行地址宽度可编程。SDRAM控制器在存储器时钟的上升沿采样输入的命令和数据。另外, SDRAM的输出数据也必须在存储器时钟的上升沿被采样。
2.1.4 存储管理模块
存储管理的功能有三个:一是确定来自1394LINK的数据帧写入SDRAM存储器0或存储器1;二是确定写入SDRAM存储器的具体地址;三是轮流读取SDRAM存储器0和存储器1的数据帧, 并写入USB芯片中的FIFO。
对于三路LINK的数据帧, 采用公平调度的方式进行读取。对SDRAM存储器的使用, 遵循以下原则:若上次写的是SDRAM存储器0, 则此次优先写SDRAM存储器1, 反之亦然;若上次写的是SDRAM存储器0, 但此时SDRAM存储器1仍在使用中, 则分配SDRAM存储器0, 反之亦然。对每个SDRAM存储器空间的分配, 采用将SDRAM存储器平分为2 KB大小块的方法, 每写入一个帧就分配一个2 KB的空间, 每读取一个帧则释放一个2 KB的空间。
2.1.5 命令解析
用于解析来自PC机的USB消息, 并做出正确的响应;USB消息主要包括读控制帧、写控制帧、读数据帧指令, 命令解析模块将USB消息进行正确解析后, 向USB FIFO写入读响应帧、写响应帧或者所要读取的数据帧, 从而完成与主机进行命令交互。
2.1.6 寄存器管理
FPGA需要管理两类寄存器的读写操作:FPGA内部寄存器和链路层寄存器。FPGA内部寄存器主要存放FPGA配置信息、逻辑控制及信息统计等功能, 而链路层寄存器则完成链路层芯片配置、数据收发等功能。上位机可以通过向FPGA发送USB消息, 调用寄存器管理模块完成对寄存器的管理[4]。
2.1.7 USB接口控制器
用于管理对USB芯片的读写操作。为保证FP-GA与USB芯片的正常通信, 要求USB芯片必须将接口配置为16位的同步SLAVE FIFO模式, 且仅使用端点2作为读FIFO, 端点6作为写FIFO。所有的控制信号均为低有效。FPGA与USB芯片之间的信号连接见图4所示。
当USB芯片EMPTY信号有效时, FPGA即发起对端点2的读操作, 直到读空为止。FPGA要进行对端点6的写操作时, 只要FULL信号无效, 就可以持续的写, 直到FULL信号有效;或者由FPGA主动令PKTEND有效, 以表示一次写操作的结束。为保证及时获取来自PC机的控制信息, 读操作优先于写操作。
2.2 软件设计
总线分析仪软件的设计主要分为三部分:USB固件、驱动软件和上层应用软件。其中, USB固件固化并运行在总线分析仪上, 驱动软件和上层应用软件运行在上位机的操作系统中。其结构示意如图5所示。
上层应用软件是实现总线分析功能的应用程序, 以图形界面的形式与用户的交互, 完成AS5643数据包的发送、解析、实时状态统计及总线拓扑显示等功能。上层应用软件通过调用USB驱动程序实现与总线分析仪硬件进行交互。USB驱动程序包括API函数接口和底层驱动两部分, 一方面实现了对板卡硬件的抽象, 使用户可以通过调用Windows标准API接口即可访问板卡上的资源, 另一方面实现了函数库的功能, 把板卡的相关功能以动态链接库的形式进行封装, 供上层应用程序进行使用[5]。USB固件运行在总线分析仪板卡上USB芯片内部, 主要完成USB芯片的初始化和缓冲通道的配置, 并响应驱动程序发出的命令。
2.2.1 USB固件
USB固件固化在总线分析仪板卡上的EEP-ROM中。设备上电后, USB芯片内嵌处理器将固件代码搬运到RAM中运行。USB固件作为驻留在设备内部的应用程序, 响应主机的列举请求, 实现设备的初始化配置并将主机报告配置信息;同时作为设备的控制中心, 根据用户的特定需求实现对外围设备的具体控制。
为了提高数据的传输效率, 将USB芯片的传输通道设定为Auto-In和Auto-Out模式, 数据的传输自动进行而不经过芯片内部处理器。使用EP2作为数据从PC机到USB芯片的传输通道, EP6作为数据从USB芯片到PC机的传输通道, 将USB芯片配置为Slave FIFO模式, 使用FPGA作为USB芯片的主控制器, 并采用同步批量传输模式。采用FX2固件典型架构进行USB芯片配置的固件核心代码为:
2.2.2 驱动程序
驱动程序使板卡的硬件资源抽象化, 将总线分析仪的功能封装为一个个独立的函数接口, 供上层应用软件使用。驱动程序主要包括两个部分:底层驱动程序和用户模式的API函数库。
底层驱动程序运行于操作系统的内核态, 直接控制硬件设备, 完成设备在操作系统中的注册、硬件控制、资源的控制和硬件资源接口的访问, 屏蔽了硬件环境和具体结构的差异性。其主要作用是让操作系统“认识”硬件, 并可以对硬件的基本资源进行操作[6]。操作系统可以使用统一的函数接口接收实现对不同硬件的访问。为了节约开发成本, 在此使用CYPRESS公司为CY7C68013 USB芯片定制的驱动程序。
API函数库运行于操作系统的用户态, 把某个特殊功能的函数使用对一系列操作系统标准接口进行封装, 以动态链接库的形式供应用程序进行调用[7]。总线分析仪的API函数库主要包括打开/关闭板卡、使能/禁止中断、开启/关闭监控、开启/停止记录、读写链路层寄存器、获取监控参数、清除监控计数等。
2.2.3 上层应用程序
总线分析仪上层应用程序的设计包括两部分:一是通过调用驱动程序与FPGA进行信息的交互;二是将用户输入的数据进行封装传递给驱动程序, 或者将从驱动程序获取的数据进行解析, 并显示在图形界面上。按功能划分, 可将上层应用程序分为5个功能模块:控制台模块、拓扑显示模块、状态监控模块、数据记录模块和数据发送模块, 如图6所示。各功能模块之间通过Windows消息进行通信, 控制台模块用于和驱动程序进行交互。模块之间进行通信时, 首先将数据并存入共享缓冲区中, 然后发送Windows消息通知对应的模块从共享缓冲区中获取数据进行处理。各模块功能如下。
(1) 控制台模块完成通过USB驱动程序与FPGA交互。控制台是其他各模块数据与总线分析仪板卡进行交互的接口。
(2) 拓扑显示模块通过获取总线分析仪链路层芯片相关寄存器数据, 解析出当前总线的连接拓扑关系, 并进行图形化显示供用户分析。
(3) 状态监控模块对当前总线分析仪的状态信息进行实时监控, 包括指定类型、指定速率数据包个数统计、错误包个数、总线复位次数统计、指定通道号异步流消息统计、VPC错误统计、数据包负载错误统计。
(4) 数据记录模块使能总线分析仪的监控功能, 将捕获的数据包从SDRAM传递到上位机内存中, 并在界面上进行显示数据包的详细信息, 支持多种过滤方式。
(5) 数据发送模块构造符合AS5643协议的数据包的各个字段, 发送给目的终端, 用于测试目的终端的接收功能。
3 总线分析仪验证
总线分析仪可使用Fire Spy3810进行验证。搭建验证平台如下:将总线分析仪通过USB接口与PC机相连, 通过线缆与Fire Spy3810相连, 如图7所示。
使用Fire Spy3810进行总线分析仪验证的思路为:使用Fire Spy3810构造符合AS5643协议的数据包, 发送到总线分析仪上, 通过PC2的总线分析仪上层应用软件查看总线分析仪所接收的数据包是否与Fire Spy3810所构造的数据包一致, 监控模块的计数是否与发送数据包一致, 拓扑结构是否与实际连接方式一致;通过总线分析仪构造AS5643数据包发送给Fire Spy3810, 通过PC1的软件验证所构造的包是否满足要求。
4 结束语
对基于AS5643协议的总线分析仪的设计与实现技术进行了研究, 从总线分析仪的工作原理及软硬件实现技术进行了分析。经验证平台实测结果表明, 该总线分析仪设计方案可满足基于AS5643协议的网络测试及网络监控的要求, 具有灵活性强、测试精度高、实时性强等特点, 为基于AS5643协议总线的性能评估和系统级验证提供了方法和依据。
摘要：AS5643协议以其低延时、确定性、高可靠性的特点在航空等高安全领域得到了广泛应用, 对于不同的AS5643总线产品协议符合性进行分析、测试, 是AS5643协议相关总线产品研制的关键。提出一种基于AS5643协议的总线分析仪的设计方案, 采用FPGA完成对AS5643协议总线网络实时数据的收集和监控, 并在上位机完成数据分析和参考信息的显示。文章详细讨论了分析仪的FPGA设计, 给出了软件的架构和实现方法, 并通过构建仿真验证平台进行了系统验证。实测结果表明, 该总线分析仪可以满足基于AS5643协议的总线分析需求。
关键词：AS5643,USB,总线分析,固件
参考文献
[1] 冯莎, 卢选民, 王兴亮.一种基于SAEAS5643总线协议的驱动程序设计.测控技术, 2012;31 (10) :98—100
[2] Society of Automotive Engineers.IEEE 1394b interface requirements for military and aerospace vehicle applications.SAE Aerospace Standard 5643, 2004
[3] EZ-USB FX2 Technical Reference Manual (Version 2.1) .Cypress.May 2000
[4] 刘光远, 张涛, 郑伟波.基于FPGA的数据采集系统IEEE1394接口设计.仪表技术与传感器, 2009;12 (12) :46—48
[5] 季睿, 宫亮, 杨煜普.基于PCI总线的IEEE1394接口开发.电子设计, 2009;25 (12) :203—205
[6] 王海涌, 黄江艳.一种基于IEEE1394总线的高速数据传输设备的设计.测控技术, 2009;28 (6) :65—68
张老师，我们最近在讨论一个句子的成分划分问题，有了一些分歧，想问问您的看法。句子如下。
They tend to be more independent， which is a very important factor in academic study and research， as well as giving them an advantage in terms of coping with the challenges of student life.
我们其中一方认为，which指代了they tend to be more independent整个内容，然后引导了并列的两个成分is a very important factor in academic study and research和giving them an advantage in terms of coping with the challenges of student life。主句是第一个逗号前的所有内容，which指代主句的内容，并发出两个动作—一个是“is a very important factor ...”，另一个是“gives them an advantage …”。由于有as well as存在，gives变成了现在分词形式giving。而另一方认为，“which is a very important factor … research”和“giving them … student life”是并列内容。在这个句子中，they tend to be more independent的确是主句，但第一个并列成分是“which is a very important factor ... research”，后面的“giving them … student life”其实是作主句的分词状语，与“which is a very important factor ... research”互为并列，而不认为give的发出者是which。
请问张老师怎么看呢？
简言之，上述争议为，“giving them … student life”是与定语从句的谓语部分“is a very important factor … research”并列，还是与整个定语从句“which is a very important factor … research”并列。解决这种分歧的关键在于正确理解as well as的结构和用法，这就是本期要讨论的内容。
As well as的词性、结构及语义
一般来说，as well as可以有下面三种用法，对应于不同的结构和语义。
As well as比较结构的用法
首先，我们可以把as well as看成是来自比较结构“as … as”，这里的well是一个副词，修饰动词，表达同级比较，基本意思是“与……一样好”。请看例句。
1. I can sing the song as well as he does.
我能够把这首歌唱得和他一样好。
但as well as的这个用法不是我们这里要重点讨论的。我们所要讨论的as well as是作为一个整体，连接两个并列成分，基本结构是X as well as Y。并列的X、Y成分可以是名词、代词、形容词、副词、介词短语甚至谓语动词。在这个结构里，as well as可以充当介词，也可以充当连词。在下面具体举例说明之前，我们先列表总结如下。
As well as充当介词连接并列成分
当我们把as well as用作介词时，其后可以接名词或动名词。请看例句。
2. When I came to China in 1992， a wheelchair was never seen. When I left in 2012， it was common to see people in wheelchairs. Besides that， new buildings were required to have ramps as well as steps.
我1992年来中国时，没见到有轮椅。等我2012年离开中国时，人们坐轮椅已经是司空见惯了。此外，新建楼房要求不仅要有台阶，而且要建坡道。
解析：这里的ramps是指专供残疾人轮椅使用的坡道，而steps指的就是供腿脚正常的人使用的台阶。我们知道，一般楼房有台阶这是很常见的，但坡道则出现得相对比较晚，也比较少。所以这里作者说ramps as well as steps，目的是为了强调ramps。如果要ramps与steps互换位置，则意味着楼房通常都有坡道，而台阶则少见—这显然不符合现实。
由此可见，在X as well as Y结构中，Y这个概念往往是已知的、常规的，因此无需被强调或重点介绍，而X这个概念则是新近的、少见的，需要加以强调或重点介绍。
我们还可以把as well as Y提到句首，比如下面这个例句。
3. As well as advantages there are also three main disadvantages of tourism. The first is erosion of the countryside by so many people： Paths， grass and other areas of vegetation and woodland get worn away.
除了优点之外，旅游业还有三大主要弊端。首先就是人多了会对乡村环境造成破坏，比如人行步道、草坪、其他绿地植被和林地都会遭到损害。
解析：这里as well as连接的并列成分是advantages和disadvantages，强调的是disadvantages，因此下文对旅游的缺点进行了展开叙述。
既然充当介词，那么当as well as后接动词时，自然要把动词变成动名词。比如，《朗文当代高级英语词典》上还专门列出了as well as doing something结构，并给出了下面这个例句。
4. The organization gives help and support to people in need， as well as raising money for local charities.
该组织不仅为当地慈善机构筹款，而且还对需要帮助的人提供帮助和支持。
解析：我们看到，这里的gives help and support to people in need与raising money for local charities是并列成分，这里将as well as当作介词使用，as well as后面使用了动名词raising。
As well as充当连词连接并列成分
当as well as用作连词时，相当于一个并列连词，连接两个并列成分，比如并列的谓语动词、名词短语、形容词、副词、介词短语等等。As well as充当连词的用法比充当介词的用法更常见。下面我们来看例句。
5. The organization gives help and support to people in need， as well as raises money for local charities. （接谓语动词，该句是对句5的改写）
6. A man may usually be known by the books he reads as well as the companies he keeps， for there is a companionship of books as well as of men. （接名词短语与介词短语）
常言说，观其友可以知其人，其实观其所读之书亦可知其人，因为与人为伴的不仅是人也可以是书。
7. He is courageous as well as strong. （接形容词）
他既坚强又有胆识。
8. An effective sentence expresses an idea or relationship clearly and concisely as well as grammatically. （接副词）
有效的句子在表达思想或语义关系时，不仅语法正确，而且简洁明了。
9. Love lives in cottages as well as in courts. （接介词短语）
爱情无贵贱，贫富皆有之。
问题解答
掌握了上述as well as的用法后，我们再来看文章开头的那句话。
They tend to be more independent， which is a very important factor in academic study and research， as well as giving them an advantage in terms of coping with the challenges of student life.
解析：这里as well as连接的是并列的动词短语“is a very important … research”和“giving them … student life”。作者这里把as well as用作介词，所以其后接了动名词giving。如果把as well as用作连词，则可以说成“… as well as gives them …”。另外，值得注意的是，关系代词which不是指代前面整个主句，而是指代非谓语动词短语to be more independent。因此，该定语从句可以改为以下两个简单句。
a. Being more independent is a very important factor in academic study and research.
【as与as的用法小结】推荐阅读：
关于as if虚拟语气的用法06-30
like的用法小结06-19
文言文常用句式与虚词用法07-10
典故的用法05-24
量词的常见用法06-15
thrill的用法总结06-21
过去分词详细的用法07-15
beg的用法总结07-19
文言虚词于的用法05-28
govern的用法和例句05-31
