浙江宁波万里国际学校 薛洪波 郑长青
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请看2002年高考的英语试题24题：
The mother didn’t know______ to blame for the broken glass as it happened while she was out.
A who B when C how D what
答案是 A。
这种“疑问词+不定式”构成的短语叫做不定式特殊结构。疑问词通常为who, whom, which, what, when, where, how, whether等。它在句子中的作用相当于一个名词短语，可以作主语、宾语、表语和同位语。
1．主语
Who to fly first is not clear.
Where to have the basketball game worried us a lot.
How to swim is more important.
It’s a problem what to do next.
2.宾语
Don’t forget when to start the machine.
I wonder whether to leave or stay.
I don’t know who to speak to. (=I don’t know to whom to speak.)
Please tell me when to use the vacuum cleaner.
I’ll show you how to start the laptop.
由上面的例句可以看出不定式特殊结构可以作两类动词的宾语：
（1） 能接不定式特殊结构作宾语的单宾动词有consider, decide, explain, find out, forget, hear, know, learn, remember, see, understand, wonder等。
但是应该注意：
a. learn how to do something 与learn to do something在含义上没有区别，如：
Lily learnt how to swim quickly. = Lily learnt to swim quickly.
b. 不定式特殊结构也可以作介词宾语，如：
They were quarrelling about who to feel the elephant first.
Peter has no idea of how to operate on the mouse.
c. 作宾语的不定式特殊结构有时可以转换成作主语的不定式特殊结构，如：
We haven’t decided which to choose.
= Which to choose hasn’t been decided.
这里主动的不定式表示了被动的含义。
(2) 能接不定式特殊结构作宾语的双宾动词有advise, ask, show, teach, tell等，此时，间接宾语就
是不定式特殊结构的逻辑主语，如：
I’ll advise you where to start.
Bill showed me how to drive the plane.
3.表语
The most important is where to hold the meeting.
What I want to learn is how to use Windows XP.
The question is when and where to go to see the film.
注意：作表语的不定式特殊结构有时可以转换成作主语的不定式特殊结构，如：
The problem is what to do next.
=What to do next is the problem.
=It’s a problem what to do next.
4.同位语
One problem---which course to choose---worried me for hours.
I’ve met a puzzle where to put all these books.
从以上例句可以看出不定式特殊结构的意义和句法功能，其用法可以归纳为口诀，以便于记忆：
（不定式特殊结构）
没有进行时态，
没有被动语态，
没有why。
凡是规律都有例外，而例外恰好证明了规律的存在。why可以与不带to 的不定式连用，如：
Why not sit here? (建议)
Why sit here? (责备)
最后，还要注意介词的介入， 如：
At that time, we lacked words in which to express our thanks.
此时，介词in 与 不定式特殊结构构成介词短语，相当于一个定语从句，修饰words，即：
At that time, we lacked words in which we could express our thanks.
原句仍然可以转换为不定式，即：
At that time, we lacked words to express our thanks in.
又如：
The factory has bought a new machine with which to make the spare parts.
=The factory has bought a new machine with which they can make the spare parts.
=The factory has bought a new machine to make the spare parts with.
Mary is not a person on whom to rely.
=Mary is not a person on whom you may rely.
=Mary is not a person to rely on.
不定式特殊结构看似简单，但是运用起来要注意方方面面。运用不定式特殊结构时，我们首先应该关注一般规律，然后留意例外的特殊情况，那么就不会犯挂一漏万的错误。
主要参考书：
薄冰 英语语法札记 第五辑 外语教学与研究出版社 1999
L. G. 亚历山大 朗文英语语法 外语教学与研究出版社 1991
Michael Swan PRACTICAL ENGLISH USAGE Oxford University Press 1995
章振邦 新编英语语法 上海译文出版社 1981