as与which引导非限定性定语从句用法浅谈

英语语法

as与which引导非限定性定语从句用法浅谈as与which引导非限定性定语从句用法浅谈
back
　　从历年的NMET试题来看，定语从句是必考的语法项目之一。特别是遇到as和which引导
非限定性定语从句的题目，同学们更是束手无策，笔者在平时的教学中，收集了一些这方面的材料，为了便于掌握运用，现将其用法试作总结归纳并举例加以说明。
　首先，as和which都可以表示主句在意义上的连贯，在从句中作主语，或用作及物动词的宾语，如，
　He married her， which／as was natural．
　I was very useful to him， which as he realized．
　但下列情况下as和which一般不能互换：
　1．as既可以指前面提到过的事实或情况，因此as可以放在句首、句末，也可以插入主句中，而which指前面提到的事实或情况，一般放在主句之后（有时也可用as），如：
　As our teacher points out， that book is of benefit to everyone．
　Heat is a form of energy， as is known to all of us．
　This machine， as might be expected， has stopped operating．
　2．as含有正如、按照、正像之意，as一般用在肯定句中，而which则 多用于含否定意义的句子中，如：
　He failed in the exam again， as was expected． He failed in the exam
again， which was unexpected．
　3．当定语从句所修饰的主句内容是谓语动词的对象时，常用as，如：
　Jack was admitted into the university， as we had expected．
　4．下列固定结构，一般不能用which，如：
　as has been said before 如前所述
　as often happens 正像经常发生的那样
　as is well known 众所周知
　as will be shown in Fig 3 将如图3所示
　as we know 正如我们知道的那样＂
　as may be imagined 这可以想象得出来
　as we all can see 正如我们大家看到的那样
　5．当关系代词代表主句引起的结果，又做主谓宾补（svoc）结构中的主语时，多用which，如：
　　He saw the girl， which delighted him．
　He didn＇t pass the exam， which made his mother angry．
　6．在从句中作介词宾语时，用which，如：
　We didn＇t go to the film， instead of which we went to the theatre．
　7．在从句中作定语时，常用which，如：
　I told her to see a doctor， which advice she took．
　8．在从句中代表主句中的谓语的整个概念时，常用which，如：
　He can write a letter in English， which I can not．
　9．指代主句中一个名词时，多用which，如：
　I gave him an interesting book， which he sta