用作介詞的to

　　to 有兩種用法：一為不定式+動詞原形; 一為介詞+名詞/動名詞， to 在下面的用法中是第二種，即to+ 名詞/動名詞：admit to承認，confess to承認，be accustomed to 習慣于，be used to 習慣于，stick to 堅持，turn to開始，著手于，devote oneself to 獻身于，be devoted to 致力于， look forward to 盼望，pay attention to

　　注意

　　省to 的動詞不定式

　　1) 情態動詞 ( 除ought 外，ought to)：

　　2) 使役動詞 let, have, make：

　　3) 感官動詞 see, watch, look at, notice , observe, hear, listen to, smell, feel, find 等后作賓補，省略to。

　　注意

　　在被動語態中則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前是動詞do時，后面出現的動詞用不帶to的動詞不定式。

　　8) 由and, or和than連接的兩個不定式，第二個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.　他應該是個好人。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 的動詞不定式，當其用于被動時，to 不可省略。

　　動詞不定式的否定式

　　Tell him not to shut the window…

　　She pretended not to see me when I passed by. 我走過的時候，她假裝沒看見。

　　典型例題

　　1) Tell him ___ the window.

　　A. to shut not　 B. not to shut　 C. to not shut　 D. not shut

　　答案：B。 tell sb to do sth 的否定形式為tell sb not to do sth。

　　2) She pretended ___ me when I passed by.

　　A.　not to see　 B. not seeing　　C. to not see　 D.　having not seen

　　答案：A。 pretend 后應接不定式。其否定形式為pretend not to do sth.。

　　3) Mrs. Smith warned her daughter ___ after drinking。

　　A. never to drive　 B. to never driver　C. never driving　 D. never drive

　　答案：A。warn sb to do sth. 的否定形式為warn sb not to do sth. 此處用的是否定詞never。

　　4) The boy wanted to ride his bicycle in the street，but his mother told him ____.

　　A. not to　　B. not to do　　C. not do it D. do not to

　　答案：A。not to 為not to do it 的省略形式。可以只用to這個詞，而不必重復整個不定式詞組。及物動詞do后應有名詞、代詞等，否則不對，因此B，D不對。

　　5) The patient was warned ___ oily food after the operation。

　　A. to eat no　 B. eating not　 C. not to eat　D. not eating

　　答案：C。warn一詞要求后用不定式，此處為不定式的被動，否定形式為be warned not to do。