7.9 省to 的動(dòng)詞不定式
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1) 情態(tài)動(dòng)詞 ( 除ought 外,ought to):
2) 使役動(dòng)詞 let, have, make:
3) 感官動(dòng)詞 see, watch, look at, notice , observe, hear, listen to, smell, feel, find 等后作賓補(bǔ),省略to。
 
注意:在被動(dòng)語(yǔ)態(tài)中則to 不能省掉。
  I saw him dance.
 =He was seen to dance.
  The boss made them work the whole night.
 =They were made to work the whole night.
4) would rather,had better:
5) Why… / why not…:
6) help 可帶to,也可不帶to, help sb (to) do sth:
7) but和except:but前是動(dòng)詞do時(shí),后面出現(xiàn)的動(dòng)詞用不帶to的動(dòng)詞不定式。
8) 由and, or和than連接的兩個(gè)不定式,第二個(gè)to 可以省去:
9) 通常在discover, imagine, suppose, think, understand等詞后,可以省去to be: 
   He is supposed (to be) nice. 他應(yīng)該是個(gè)好人。

舉例:
   He wants to move to France and marry the girl.
He wants to do nothing but go out.

比較:  He wants to do nothing but go out.
     He wants to believe anything but to take the medicine.

典型例題
1) ---- I usually go there by train. 
  ---- Why not ___ by boat for a change? 
  A. to try going  B. trying to go  C. to try and go  D. try going  
  答案:D. why not 后面接不帶to 的不定式,因此選D。

2) Paul doesn't have to be made ___. He always works hard. 
  A. learn  B. to learn  C. learned  D. learning
  答案:B. make后接不帶to 的動(dòng)詞不定式,當(dāng)其用于被動(dòng)時(shí),to 不可省略。