三.語法知識：非謂語動詞(不定式)
動詞不定式的形式及特點
動詞不定式一般由to+動詞原形構成，其否定式是not to do.
動詞不定式的用法：
1． 作主語
1).可以直接作主語,謂語動詞需用單數。如： To see is to believe．
練一練：To study English hard ______ very important.
2).但在英語中，常用it作形式主語，真正的主語即動詞不定式放在后面，避免頭重腳輕，如：
It's wrong to play tricks on other people．
It's our duty to keep our environment clean and tidy．
規律：動詞不定式在句中作主語時，常放在It is ＋adj．（形容詞）＋to do sth．或 It is ＋n．（名詞）＋to do sth．句型中，it僅作形式主語,真正的主語是動詞不定式。
練一練：It’s so easy for me _____ _____ (do) that.
It’s necessary for you _____ ______(lock) the car when you do not use it.
It’s my turn _____ ______ (clean) the classroom.
2．作賓語
1)Want decide ，agree ,ask,hope,wish,learn,expect,pretend,refuse,promise,等動詞后面跟并且只能跟不定式。如：
We agreed to start early．
She wants to be a doctor．
2).love，like ，begin，start，hate ，prefer等詞后面可以接不定式。
規律：上述動詞后面除接不定式外，還可以接動名詞，意思無很大區別。
提示板：like doing指經常性動作，而like to do指一次性的動作。如：
I like swimming，but I don't like to swim now．我喜歡游泳，但我現在不想游。
3).stop，forget，remember，go on ，try等詞或短語后面可以接不定式，還可以接動名詞。
規律：上述動詞后面接不定式和接動名詞意思大不相同。
提示板：
1.stop to do sth．：停止一件事，去做另一件事。
stop doing sth．：停止正在做的事。
2.forget to do sth表示“忘記”將要做的事
forget doing sth表示“忘記”曾經做過的事
3. remember to do 意思是記住去做某事,表示這件事情還沒有做.
remember doing 意思是記得做過某事,表示這件事情還已經做了
4. stop to do sth．：停止一件事，去做另一件事。
stop doing sth．：停止正在做的事。
5.go on doing sth 是指繼續做同一件事，
go on to do sth 是指繼續去做另一件事
6. try to do sth.嘗試去做某事 try doing sth. 盡力做某事
練一練：
1、I forgot _____________ (ask) Tom. 我忘了去問湯姆。
2、I’ll never forget _________(meet) you that afternoon. 我永遠不會忘記那天下午見到你的情況。
3、Remember____________( turn off) the lights when you leave the room. 在你離開房間之前,記得把燈關了.
4、I remembered______________( turn off) the lights when I left the room. 我記得我關燈了,當我離開房間的時候.
5、After having a rest,I went on _______(do) homework. 休息一會后，我繼續做作業.（休息前就在做此事）
6.After cleaning the floor,I went on ______ (clean) the window. 擦完地后，我又繼續擦玻璃.
4).在find／feel＋it＋adj．＋to do sth．句型中，it是形式賓語，真正的賓語是后面的動詞不定式。如：
The man downstairs found it difficult to get to sleep．
I feel it easy to recite the text．
練一練：
He finds it interesting ______ (read) the book
They feel it hard ________ (finish) the task on time.
3．作賓語補足語
1).tell，ask，want，order，teach，invite，warn，wish，help，get，wish，help等詞后面常接不定式作賓補。如：
I tell him not to go there by bus ．
Edison's mother taught him to read and write．
2).let，make，have，see，hear，feel，watch， notice后面接不帶to的不定式作賓補。如：
The boss makes them work 16 hours a day． I heard her sing in the next room．
提示板：若變成被動語態，在上述結構中，不定式符號to要加上。如：
They are made to work 16 hours a day by the boss．
She was heard to sing in the next room．
練一練：
Though he often _______(make) his sister cry, today he was ________ (make)cry by his sister.盡管他總是弄哭他妹妹，今天卻被妹妹弄哭了。
They ask her ______( leave )the country.
4．作定語：放在被修飾的名詞、代詞后面
例句：I have a lot of work to do．
The doctor said he could do nothing to help the boy．
規律：動詞不定式若在句中作定語，常放在被修飾的名詞、代詞之后。
提示板：如果動詞不定式和前面所修飾的詞構成動賓關系，若動詞是不及物動詞，切記不要忘掉介詞。如：
I have a small bedroom to live in．
Have you got some pens to write with？
練一練：
①The next train ________ (arrive) is from Washington.
②Have you anything to be taken to your sister?
③Do you have anything _______( say) on the question?
④Would you please give me some paper ________(write )on?
⑤My wish ______( visit) France has come true at last.
5．表語：放在be動詞,感官動詞，三變turn, become,get,后面
例句：His wish is to become a scientist．
The first important thing is to save the soldiers' lives． 當務之急是搶救戰士們的生命。
規律：動詞不定式在句中作表語時，通常對連系動詞前面的名詞進行詮釋說明。
My work is _______(clean )the room every day.
6.作狀語：修飾動詞，表目的，結果，原因。
To catch the bus, I got up early.
7.不定式和疑問詞連用作賓語。
When to do/ How to do /What to do/Why to do/Where to do/Which to do
例如：Do you know how to get to the zoo? 你知道怎么到動物園嗎