1． 作介詞的to
to 有兩種用法： 一為不定式+動(dòng)詞原形； 一為介詞+名詞/動(dòng)名詞, to 在下面的用法中是第二種，即to+ 名詞/動(dòng)名詞：
admit to承認(rèn)， confess to承認(rèn)，
be accustomed to 習(xí)慣于， be used to 習(xí)慣于，
stick to 堅(jiān)持， turn to開始，著手于，
devote oneself to 獻(xiàn)身于， be devoted to 致力于，
look forward to 盼望， pay attention to 注意
2． 省to 的動(dòng)詞不定式
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
3． 動(dòng)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(shí)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(yīng)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�？梢灾挥胻o這個(gè)詞，而不必重復(fù)整個(gè)不定式詞組。及物動(dòng)詞do后應(yīng)有名詞、代詞等，否則不對(duì)，因此B，D不對(duì)。
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(dòng)，否定形式為be warned not to do。
4． 不定式的特殊句型too…to…
1）too…to 太…以至于…
He is too excited to speak.
他太激動(dòng)了，說不出話來。
---- Can I help you ? 需要我?guī)兔?
---- Well, I'm afraid the box is too heavy for you to carry it, but thank you all the same. 不用了。這箱子太重，恐怕你搬不動(dòng)。謝謝您。
2) 如在too前有否定詞，則整個(gè)句子用否定詞表達(dá)肯定， too 后那個(gè)詞表達(dá)一種委婉含義，意 為"不太"。
It's never too late to mend. (諺語)
改過不嫌晚。
3) 當(dāng)too 前面有only, all, but時(shí)，意思是：非�！� 等于very。
I'm only too pleased to be able to help you. 我非常高興能幫助你。
He was but too eager to get home. 他非常想回家。
5． 不定式的特殊句型so as to
1） 表示目的；它的否定式是so as not to do。
Tom kept quiet about the accident so as not to lose his job.
湯姆對(duì)事故保持沉默是為了不丟掉他的工作。
Go in quietly so as not to wake the baby.
輕點(diǎn)進(jìn)去，別驚醒了嬰兒。
2) so kind as to ---勞駕
Would you be so kind as to tell me the time?
勞駕，現(xiàn)在幾點(diǎn)了。
6． 不定式的特殊句型Why not
"Why not +動(dòng)詞原形"表達(dá)向某人提出建議，翻譯為："為什么不……?" "干嗎不……?"
例如：
Why not take a holiday?
干嗎不去度假?
7． 不定式的時(shí)態(tài)和語態(tài)
時(shí)態(tài)\語態(tài) 主動(dòng) 被動(dòng)
一般式 to do to be done
進(jìn)行式 to be doing
完成式 to have done to have been done
完成進(jìn)行式 to have been doing
1) 現(xiàn)在時(shí)：一般現(xiàn)在時(shí)表示的動(dòng)詞，有時(shí)與謂語動(dòng)詞表示的動(dòng)作同時(shí)發(fā)生，有時(shí)發(fā)生在謂語動(dòng)詞的動(dòng)作之后。
He seems to know this.
I hope to see you again. = I hope that I'll see you again. 我希望再見到你。
2) 完成時(shí)：表示的動(dòng)作發(fā)生在謂語動(dòng)詞表示的動(dòng)作之前。
I'm sorry to have given you so much trouble.
He seems to have caught a cold.
3) 進(jìn)行時(shí)： 表示動(dòng)作正在進(jìn)行，與謂語動(dòng)詞表示的動(dòng)作同時(shí)發(fā)生。
He seems to be eating something.
4) 完成進(jìn)行時(shí)：
She is known to have been wreaking on the problem for many years.
8． 動(dòng)名詞與不定式
1） 動(dòng)名詞與不定式的區(qū)別：
動(dòng)名詞表達(dá)的是： 狀態(tài)，性質(zhì)，心境，抽象，經(jīng)常性，已發(fā)生的
不定式表達(dá)的是： 目的，結(jié)果，原因，具體，一次性，將發(fā)生的
2） 接不定式或動(dòng)名詞，意義相同。
3） 動(dòng)名詞與不定式語義不同的有11 組：
1 stop to do stop doing
2 forget to do forget doing
3 remember to do remember doing
4 regret to do regret doing
5 cease to do cease doing
6 try to do try doing
7 go on to do go on doing
8 afraid to do afraid doing
9 interested to do interested doing
10 mean to do mean doing
11 begin/ start to do begin/ start doing