1.This is one of the best books__on the subject.
A. that have ever been written B. which have ever been written
C.that has ever been written D.whatever have been written
答案是A 这里B为什么不可以
2.We were not surprised at ____, for he had worked so hard.
A. what has he achieved B.that what he had achieved
C. what he had achieved D.that he had achieved
答案是C 有点不明白 that为什么不可以引导
3.My room is a mess.It needs ____.
A. to be tidying up B.tidying up C.to tidy up D.tidied up
答案是B 我想知道need的用法 A为什么不可以
谢谢
1 定语从句先行词被最高级修饰时，只能用“that”引导
2 宾语从句.如：I don't know what he said.“我们对他所取得的成绩并不惊奇，因为他工作很努力。”
3 need 做为实义动词（1）Sb need(s) to do sth.
(2) Sth need(s)doing
如：I need to clean my room.
The flower needs watering.
1、表示解释说明用that，表示特指用which
2、是宾语从句所以用what引导
3、need主动形式的动名词doing具有被动的含义，need后面需要接带to的动词不定式,表示有义务或责任去做某事。
1、有最高级时要用that
2、这里是宾语从句，不是定语从句
3、用B的意思是用主动，表被动，而A不能够表示被动的意思
1、因为在定语从句中如果含有最高级词语作为先行词时用that 而不用which
2、在这一题目中，at 后面缺少宾语，而what 引导的句子可以做宾语，所以用what 而不用that
3、need doing sth 某事需要被做
need to do sth 需要做某事