1. but作為關系代詞常與具有否定或疑問意義的主句連用,其引導的從句修飾的先行詞多是否定意義的,but=who ... not/which ... not/that ... not,意為“無不/沒有不/誰不”。
There's no one but knows the importance of English.
沒有不懂得英語重要性的人。
Not a single room in this hotel but is empty.
這個賓館沒有一個房間不是空的。
2. who ... but(=that ... not)意為“誰不……的?”
Who is there but makes some mistakes?
Who is there that does not make any mistakes?
人哪有不犯錯誤的?
3. what引導定語從句時既可指人也可指物,指人時what=the person(s) that,指物時what=the thing/all/everything that。
That is exactly what he told me.
that is exactly The thing he told me.
那正是他告訴我的。
4. what本身的作用已經包含有先行詞和關系代詞。有一身兼兩職的作用,分別在主句和從句中作相應的成分。
Don't do what you shouldn't do.
不要做你不應該做的事。
Never pretend to know what you really don't know.
不要假裝知道你并非真正知道的事情。
5. 用what時,前無先行詞;若有先行詞,應視其情況選擇使用that, which,或who。
What can be done has been done.
能做的都已經做了。
All that can be sold has been sold.
所有能賣的都已經賣了。
I have known everything that you want to tell me.
我已經知道了你想告訴我的一切。
專項練習
1. Generally speaking, there is no one _______ loves their parents in the world.
A. that
B. but
C. who
D. A or B or C
2. All _______ is needed is a supply of oil.
A. the thing
B. that
C. what
D. which
3. _______ is over is over.
A. What
B. That
C. What all
D. All what
4. _______ were once truth are true no longer.
A. What
B. That
C. Which
D. All
5. _______ you have done might do harm to other people.
A. That
B. What
C. Which
D. This
6. A computer can only do _______ you have instructed it to do.
A. how
B. after
C. what
D. whom
7. They want to know _______ do to help us.
A. what can they
B. what they can
C. how they can
D. how can they
8. This is the longest train _______ I have ever seen.
A. which
B. that
C. what
D. whom
9. Who studies here _______ wants to go to college?
A. that
B. but
C. who
D. whom
10. There's none of us _______ wishes to go to Tsinghua University.
A. but
B. that
C. who
D. which
答案速查 1-5 BBAAB 6—10 CBBBA