动词不定式的构成形式为"to+动词原形"，to为动词不定式的符号，本身无意义。
一、动词不定式作主语 动词不定式作主语时，可以直接放在谓语动词前面的主语位置，也可以用先行词it作形式主语，而将真正的主语(不定式)置于后面。常见的句式有：

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

句式(1)中常用nice， kind， clever， good， right， wrong， foolish， careless等形容词，与介词of搭配，这些形容词常表述不定式逻辑主语的属性或性质;

句式(4)中常用hard， difficult， easy， important等形容词，与介词for搭配，表示不定式表示的动作、行为的性质。 1. It's our duty _________ the room every day. A. to clean B. cleaned C. clean D. cleans(甘肃省)

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

3.建造这座立交桥将花费工人们一年多的时间。 It will _________ the workers over a year _________ _________ the flyover.(北京市海淀区)

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、动词不定式作宾语 在want， like， agree， hope， wish， learn， begin， start， seem， decide， hate， choose， forget， remember等动词后面，可以接不定式作宾语。如果其后接形容词补足语时，则可以用it作形式宾语，而把作真正宾语的不定式放到后面。 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、动词不定式作宾语补足语 不定式可以用作宾语补足语。后面可以接不定式作宾语补足语的动词有：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 (江苏省) 2. Mr Li often teaches his Japanese friends ______ Chinese food. A. cook B. cooks C. to cook D. cooked (甘肃省) Key： 1. B 2. C
四、动词不定式作状语 go， come， try， do / try one's best等动词或短语动词作谓语时，其后常常可以接不定式作目的状语。

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 +形容词+ to do sth"结构中的不定式作状语，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 (甘肃省) Keys： 3. D 4. B 5. A 在上述"too +形容词/副词(for sb)to do…"(太……而不能……)和"enough (for sb) to do…"(足以、足够……做……)结构中，不定式作结果状语。

6. The panda is so fat that it can't go through the hole.(改为意思相同的句子) The hole ______ ______ ______ ______ such a fat panda to go through. (广东省)

7. The ice on the lake was so thin that people couldn't skate on it. (改为意思相同的句子) The ice on the lake wasn't ______ enough ______ people ______ ______ ______. (广东省) Keys： 6. is， too， small， for 7. thick， for， to， skate， on
五、动词不定式作定语 不定式作定语时，常放在被修饰的词语之后，与被修饰的词语为逻辑上的主谓关系或动宾关
系;如果不定式的动词是不及物动词，其后要加上必要的介词或副词，构成的短语动词相当于及物动词。 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 (山东省) Key： 1. C 2. D 3. D