as与 which的区别

as 和 which 引导定语从句的区别

我们先看两道高考题：

1．_____ is known to all，China will be an _____ powerful country in 20

or 30years'time．

A．That；advancing B．This；advanced C．As；advanced D．It；advancing

2．He made another wonderful discovery，_____ of great importance to science．

A．which I think is B．which I think it is C．which I think it D．I think is

分析：第一题考查了as在从句中作主语的定语从句，意为“正如”，而ad- vanced

country表示发达国家；第二题考查了which引导的非限制性定语从句，I think是插入语。这两个句子分别含有as和which引导的定语从句，现就其用法作一说明：

一、as引导的定语从句表示说话人对话语的看法、态度、依据、解释或评论。具有下列特点：

1．as用于引导定语从句时，具有“正如……、像……、由……而知”等语义。如：

He was strongly against the plan，as could be expected．（正如所料，他强烈反对这项计划。）As he hoped he would，he saw the girl．（像他希望的那样，他见到了那个女孩。）

2．as引导的定语从句在语义上要和主句保持一致，而which可不一定，如果语义不一致，则要用which来替代as。如：

He married again，as（which）was natural．（他又结婚了，这是自然的。）

3．as引导的定语从句，其先行词可由以下词来修饰，the same ／such ／as等。也可以由which来改写，但不可直接替换。如：

This is the same sum as was spent in that year on private motoring．＝This is

the sum which was spent in that year on private motoring．（这与那年用于私人汽车所花的费用相同。）

4．as引导的非限制性定语从句可放在主句之后，也可放在主句之前。但which只能放在主句之后。如：

As we have seen，oceans cover more than 70％of the earth．（如我们所见，海洋覆盖地球70％多的面积。）

He seemed a foreigner，which in fact he was．（他看上去像个外国人，事实上他就是。）5．as在定语从句中作宾语时，从句的谓语动词常是see ／watch ／know ／hear等表示感知的动词，且谓语动词前带有情态动词can ／could ／may等，此外常用的动词还有say ／tell ／remember等。如：

It was true，as everybody could know．（这是真的，大家都知道。）

6．as在定语从句中作主语时，其谓语动词可以是及物动词的被动语态，也可以是be或其它连系动词。如是不及物动词，则不存在以上关系。可以说as often hap- pens（appears）等。如：

He came back yesterday，as was ex- pected．（他如期昨日返回。）

二、which引导的此类从句，是对主句所叙述的事情进行补充说明，表明事物的状态或结果。一般有下列特点：

1．如果定语从句的谓语是行为动词的主动语态，且关系代词在从句中作主语时，一般要用which，这时which可以用and that改写为并列句。如：

Things then greatly changed，which surprised us．＝Things then greatly changed，and that surprised us．（那时事情巨变，使我们惊讶。）

2．由“介词＋关系代词”引导的关系分句多用于正式文体中，常用“介词＋which”，不用“介词＋as”。如：

They tried to think of a plan by which they could finish their task ahead of time．（他们试图想个计划，以便提前完成任务。）

三、在与上述几条不冲突的情况下，as和which可以换用。如：

A horse is a useful animal，as ／which everybody knows．（众所周知，马是有用的动物。）

练习：

1．Dorothy was always speaking highly of her role in the play，_____ ，of course，made the others unhappy．（NMET 2000）

A．who B．which C．this D．that

2．The weather turned out to be very good，_____ was more than we could expect．

A．what B．which C．that D．it

3．In the office I never seem to have time until after 5：30P．M．_____ many people have gothome．（上海95）

A．whose time B．that C．on which D．by which

4．_____ ，the Great Wall came into being in Qin Dynasty．

A．It's clear B．We all know C．As we all know D．Which we all know

5．As many members were present _____ agreed to the plan．

A．who B．that C．which D．as

6．_____ is known to everybody，the moon trav- els round the earth once every month．（NMET 2001）

A．It B．As C．That D．What

（参考答案：1．B 2．B 3．D 4．C 5．D 6．B）