動詞不定式的構(gòu)成形式為"to+動詞原形"，to為動詞不定式的符號，本身無意義。
一、動詞不定式作主語 動詞不定式作主語時，可以直接放在謂語動詞前面的主語位置，也可以用先行詞it作形式主語，而將真正的主語(不定式)置于后面。常見的句式有：

(1)It is +形容詞(of sb)to do sth. (2)It is +名詞(for sb)to do sth. (3)It takes sb some time to do sth. (4)It is +形容詞(for sb)to do sth.

句式(1)中常用nice， kind， clever， good， right， wrong， foolish， careless等形容詞，與介詞of搭配，這些形容詞常表述不定式邏輯主語的屬性或性質(zhì);

句式(4)中常用hard， difficult， easy， important等形容詞，與介詞for搭配，表示不定式表示的動作、行為的性質(zhì)。 1. It's our duty _________ the room every day. A. to clean B. cleaned C. clean D. cleans(甘肅省)

2. It's hard for us _________ English well. A. learn B. learns C. to learn D. learning(江西省)

3.建造這座立交橋?qū)⒒ㄙM工人們一年多的時間。 It will _________ the workers over a year _________ _________ the flyover.(北京市海淀區(qū))

4. It's very nice _________ you to get me two tickets _________ the World Cup. A. for， of B. of， for C. to， for D. of， to(安徽省) Keys： 1. A 2. C 3. take， to， build 4. B
二、動詞不定式作賓語 在want， like， agree， hope， wish， learn， begin， start， seem， decide， hate， choose， forget， remember等動詞后面，可以接不定式作賓語。如果其后接形容詞補足語時，則可以用it作形式賓語，而把作真正賓語的不定式放到后面。 1. He wants ______ some vegetables. A. buy B. buying C. to buy D. buys (山西省) 2. Don't forget ______ your homework with you when you come to school. A. to bring B. bringing C. to take D. taking (福建省) 3. He found it very difficult ______. A. sleeping B. sleepsC. slept D. to fall asleep (湖南省) Keys： 1. C 2. A 3. D

三、動詞不定式作賓語補足語 不定式可以用作賓語補足語。后面可以接不定式作賓語補足語的動詞有：ask， teach， expect， tell， allow等。 1. Robert often asks us ______ his Chinese, so his Chinese is much better than before. A. help him B. to help him with C. to help with D. helps him with (江蘇省) 2. Mr Li often teaches his Japanese friends ______ Chinese food. A. cook B. cooks C. to cook D. cooked (甘肅省) Key： 1. B 2. C
四、動詞不定式作狀語 go， come， try， do / try one's best等動詞或短語動詞作謂語時，其后常常可以接不定式作目的狀語。

1. She went ______ her teacher. A. to see B. looks C. saw D. seeing (江西省)

2. Meimei likes English very much. She does her best ______ English well. A. learn B. learning C. to learn D. learns (四川省) Key： 1. A 2. C "be +形容詞+ to do sth"結(jié)構(gòu)中的不定式作狀語，常表示原因或方式

3. I'm sorry ______ that. A. hears B. hearing C. hear D. to hear (河北省)

4. I'm sorry ______ you. A. trouble B. to trouble C. troubling D. troubled (吉林省)

5. My mother was very glad ______ her old friend. A. to meet B. meet C. met D. meets (甘肅省) Keys： 3. D 4. B 5. A 在上述"too +形容詞/副詞(for sb)to do…"(太……而不能……)和"enough (for sb) to do…"(足以、足夠……做……)結(jié)構(gòu)中，不定式作結(jié)果狀語。

6. The panda is so fat that it can't go through the hole.(改為意思相同的句子) The hole ______ ______ ______ ______ such a fat panda to go through. (廣東省)

7. The ice on the lake was so thin that people couldn't skate on it. (改為意思相同的句子) The ice on the lake wasn't ______ enough ______ people ______ ______ ______. (廣東省) Keys： 6. is， too， small， for 7. thick， for， to， skate， on
五、動詞不定式作定語 不定式作定語時，常放在被修飾的詞語之后，與被修飾的詞語為邏輯上的主謂關(guān)系或動賓關(guān)
系;如果不定式的動詞是不及物動詞，其后要加上必要的介詞或副詞，構(gòu)成的短語動詞相當于及物動詞。 1. Would you like something ______? A. drink B. drinking C. to drink D. drinks (湖北省) 2. I have a lot of homework ______. A. do B. doing C. did D. to do (河南省) 3. He is not an easy man ______. A. get on B. to get on C. get on with D. to get on with (山東省) Key： 1. C 2. D 3. D?