一、“疑問詞＋不定式”結(jié)構(gòu)中的疑問詞,包括疑問代詞who,what,which和疑問副詞how,when,where等.這些疑問詞和不定式一起構(gòu)成了不定式短語,這種結(jié)構(gòu)可在句子中作主語、賓語、表語等.例如：
①How to do it is aquestion．該怎樣做倒是一個(gè)問題.（作主語）
②I really don't know what to write about．我實(shí)在不知道該寫些什么.（作動(dòng)詞賓語）
③We must first solve the problem of whom to serve．我們必須首先解決為誰服務(wù)的問題.（作介詞賓語）
④The question is where to put it．問題是該把它放在哪兒才好.（作表語）
⑤I asked him how to learn English．我問他如何學(xué)習(xí)英語.（作賓語補(bǔ)足語）
二、“疑問詞＋不定式”結(jié)構(gòu)相當(dāng)于一個(gè)名詞性從句,常?？捎猛瘸煞值膹木浯?改寫時(shí)只需在疑問詞后加一適當(dāng)主語,并將不定式改成適當(dāng)形式的謂語.上述例句可以分別改寫成：
①How we should do it is a question．
②I really don't know what I should write about．
③We mustfirst solve the problem ofwhom we should serve．
④The question is where we should put it．
⑤I asked him how we should learn English．
三、“疑問詞＋不定式”結(jié)構(gòu)經(jīng)常放在tell,show,teach,learn,know,wonder,discuss,re- member,forget,find out等動(dòng)詞（詞組）之后作賓語.例如：
The teacher told the students how to do the experiment．老師教學(xué)生如何做實(shí)驗(yàn).（句中 told含有taught的意思）
The young woman doesn't know what to do．那位年輕女子不知道怎么辦.（句中what不能改換成how）
He tells me how to answer all the questions in English．他告訴我怎樣用英語回答所有的問題.（句中的how不能省去）
另外,這種結(jié)構(gòu)可以構(gòu)成獨(dú)立問句.例如：What to do?怎么辦?
How to get rid of the trouble?如何擺脫困境?
鞏固練習(xí)：
I．用“疑問詞＋不定式”改寫下列句子.
①How we should do it was discussed last night．
____ was discussed last night．
②I didn't know where I should go．
I didn't know ____ ．
③The difficulty was how we should cross the river．
The difficulty was ____ ．
II．根據(jù)漢語補(bǔ)全下列英語譯文.
①何時(shí)動(dòng)身還不知道.
____ is unknown．
②我忘了該怎么辦.
I forgot ____ ．
③我可以告訴你哪里可以買到此書.
I can tell you ____ ．
Keys：I．① How to do it②where to go ③ how to cross the river
II．①When to start②what to do③ Where to buy（get）this book