3.关系代词which与as的用法比较

(1)当as与which引导以整个主句、整个谓语或述谓成分为先行项的非限制性定语从句时，其用法有以下的异同。首先，which和as都可在主—系—表和主—谓结构中的定语从句中作主语，在这样的结构中两者可以交替使用。

He married her，as/which was natural．

他娶了她，这是很自然的。

The ships were frozen in，as/which not infrequently happens in those regions．

这些船只被冰冻住了，这在那些地方不是不经常的事儿。

在主—系—表定语从句中，which和as还可作主语的表语，指代上文的表语部分。

He seemed a foreigner，as/which in fact he was．

他好像是个外国人，事实上也是这样。

He was not sick，as/which some of the other passengers were．

他没有生病，而其他的乘客却生病了。

This question seems not easy to answer，as indeed it is．

这个问题似乎不容易回答，但事实上却很容易回答。

which和as也都可在主—动—宾定语从句中作宾语。

He is fond of music，which/as I'm glad to hear．

他喜欢音乐，听到这个我很高兴。

I was very useful to him，which/as he realized．

我对于他是有用的，他意识到了这一点。

John was admitted into the university，as/which we had hoped．

约翰被大学录取了，这是我们早就希望的。

但是如果后面跟有宾语补足语时，不宜用as。

The old man had on a skirt，which we could find funny．

这个老人穿了一件衬衫，我们觉得这很滑稽。

(2)但在主—动—宾定语从句中作主语时，关系代词通常要用which，而不用as。

He saw the girl，which(不用as)delighted him．

他看到了那个女孩，这让他很高兴。

He won Nobel Prize in chemistry，which(不用as)made him illustrious．

他得了诺贝尔化学奖，这使他名扬天下。

Rubber is a light，elastic，durable and water-resistant material，which(不用as) makes rubber industry very important．

橡胶是一种质松、富有弹性、经久耐用和防水的材料，因此橡胶工业十分重要。

They turned a deaf ear to our demands，which(不用as)made us very angry．

他们把我们的要求当耳边风，这使我们非常生气。

(3)上述which从句和as从句的主要区别首先体现在语义上:as虽可作为关系代词，但仍多少保留“理由”、“比较”、“方式”、“等同”等意义，而关系代词which没有这些意义。因此，由as引导的定语从句通常在意义上不可与主句相悖，而且一般是肯定句，对主句意义起辅助作用，表示“正如”等意义，which从句则不受此限。试观察下列诸句:

In China，you sometimes get a hot，damp cloth to clean your face and hands，which(不用as)，however，is not the custom in Western countries．(人教大纲版高一上第38页)

在中国，你有时得到一块热的湿巾，用来擦脸和手，然而，这不是西方国家的习俗。

She has married again，which(不用as)was unexpected．

她又嫁人了，这是未预料到的。

He cheated his parents，which(不用as)was disgraceful．

他欺骗父母，那是不光彩的事情。

当然，由as引导的定语从句有时也可能带有否定词，但这种否定的定语从句通常可作正面理解，对主句意义仍起相辅的作用，而不起相悖的作用。

He turned his eyes on Philip's face，as he had not done for ten years．

他的眼睛盯着菲利普的脸，他已有十年没有这样了。

He really can't lend you the money，as you might not realize．

他不能借给你钱，这一点你可能没有意识到。

上述两句中的as从句可分别理解为:

He turned his eyes on Philip's face，as he had done ten years before．

他的眼睛盯着菲利普的脸，他十年前才这样子过。

He really can't lend you the money，as you must realize．

他不能借钱给你，这一点你必须意识到。

(4)再者，上述as从句位置比较灵活，它可以出现在句尾，也可以出现在句首或句中。至于由which引导的定语从句，则位置比较固定，通常位于句尾，而不可以移至句首。

又如:

As is often the case，we have overfulfilled the production plan．

像往常情况一样，我们已超额完成了生产计划。

Heat，as is known to all of us，is a form of energy．

正如我们所知道的，热是能量的一种形式。

We must improve our style of work，as is announced in today's newspaper．

今天报纸上说，我们必须改进工作作风。

(5)还须注意下列固定结构中的关系代词as代表整个主句，最好不用which。

as is often the case　情况常常如此

as often happens　这情况常常发生，正如经常发生的那样

as has been said before　如上所述

as may be imagined　这可以想象得出来

as might be expected　这是可能预料到的

as is well known　(这是)众所周知的

as has been pointed out　正如已指出的那样

as we all can see　正如我们大家都能看到的那样

as will be shown in　将如……所示

as we know　正如我们所知道的那样

(6)which在定语从句中作主语和宾语时，先行项可以是一个名词，而as在定语从句中作主语和宾语时，其先行项则不能是名词，而应是主句的某一部分或整个主句。

By the time he was twenty-five，he had written a book，which made him famous．

当他25岁时，他已经写了一本书，这本书使他出了名。

The film，which I saw yesterday evening，was about the Long March．

这部电影是描写长征的，昨天晚上我看了这部影片。

I found the book(in)here，which was the last place I expected to find it．

我在这儿找到了这本书，那是我绝未想到会在这儿找到的。

The story，which many people believe，is very interesting．

这个故事很有趣，许多人相信这个故事。

He is late，as is often the case．

他迟到了，这是常事。

(7)which在非限制性定语从句中可作定语，而as则不能。

I told her to see a doctor，which advice she took．

我叫她去看病，她接受了我的忠告。

(8)as能引导省略系动词be的定语从句，而which则不能。

That material is elastic，as(is)shown in the figure．

那种材料有弹性，如图所示。

As(is)announced in today's paper，we have fulfilled our production quota ahead of schedule．

今天报纸宣布，我们已经提前完成了生产指标。

(9)再者，as与which也可以引导限制性定语从句，若先行项中含the same，such，as时关系代词应用as，不能用which;可用which改写，但不可直接用which代替as。

We have never heard such interesting stories as the teacher told us．

=We have never heard the interesting stories which/that the teacher told us．

He lives in the same building as I live in．

=He lives the building which/that I live in．

Some people have no doubt that their cat understands as many words as does a dog．

=Some people have no doubt that their cat understands all the words which a dog understands．

Boxing has as unquestionable a right to the epithet“noble”，ashas a lord(贵族)himself．

=Boxing has an unquestionable right to the epithet“noble”which a lord himself has．

(10)有时，许多作者愿意在as引导的从句中加上一个“it”来代表整个句子、句子的一部分或名词短语，而把as看成是从属连词，诸如as it happens，as it appears，as I see it，as we know it等。

As it appears from her essay，she has read widely in romantic literature．

从她的文章看，她好像阅读了大量的浪漫主义文学作品。

He is the best candidate，as it seems．

他好像是最佳的候选人。

As it happens，we probably won't have all that much time for a holiday，though．

但是，碰巧我们的假期不会有那么长的时间。

As I see it，this article is quite well-written．

在我看来，这篇文章写得很好。

Usually the land was shown as a continent around the South Pole，but much larger than Antarctica，as we know it now．(人教大纲版高三第153页)

通常地图上显示南极周围是一片陆地，但是比现在我们所知道的南极洲要大得多。

(11)下面简略地讲一讲主句为否定句时as引导的定语从句的修饰范围问题。

①当as引导的定语从句位于具有否定意义的主句之前时，as从句所修饰的范围是整个主句的内容，也就是说，把否定意义也包括在内。

As has been said above，grammar is not a set of dead rules．

正如前面所说的，语法不是一套死条文。

②当as引导的定语从句位于具有否定意义的主句之后时，as从句所修饰的范围不包括否定意义。

Spiders are not insects，as many people think，nor even nearly related to them．

蜘蛛不是昆虫，许多人都这样认为，它甚至与昆虫几乎没有联系。

When he came home in 1775 he was sure that there was no great southern continent with a mild climate，as scientists had believed for hundreds of years．(人教大纲版高三第159页)

当他(库克船长)在1775年回国的时候，他确信地球最南端没有一块气候温和的大陆，而科学家在过去的数百年都是这样认为的。

③当as引导的定语从句位于具有否定意义的主句中间时，as从句所修饰的范围也不包括否定意义。

She did not，as her friend had feared，open the case．

她没有打开盒子，而她的朋友就是怕她当面打开盒子。

The facts of science are not，as some think，dry and lifeless．

科学事实并不像有些人想象的那样枯燥无味和没有生命力。