一、动词不定式作主语。动词不定式在句中作主语时,谓语动词用单数。有时为了保持句子的平衡,常用it作形式主语放在句首,而把真正的主语——动词不定式(短语)放在后面。
★考题回放                                
(    )1. To do as many exercises as possible ______ necessary before exam.
A. are    B. is      C. have      D. has
(    )2. It’s a good habit ______ breakfast every day.
A. had    B. have    C. has       D. to have
二、动词不定式作宾语与v-ing形式作宾语的区别。有些动词之后只能用v-ing形式,如:enjoy, mind, practice, keep等;有些动词之后只能用动词不定式,如:afford, agree, decide, fail等;有些动词之后既可用v-ing形式又可用动词不定式,二者没有什么区别,如:continue, begin, learn, like等;有些动词之后用v-ing形式和动词不定式意义有所不同,如:try, forget, mean, remember等
★考题回放                                
(    )3. —Oh, terrible! I forgot ______ the window. It’s windy.
—Really? Let’s go back home quickly.
A. closing B. to close    C. closed     D. close
三、动词不定式作宾补。多数动词的后面跟带to的动词不定式作宾补,但某些感官动词(如:see, hear, feel, watch等)和使役动词(如:make, let, have等)在主动句中要求用省去to的动词不定式作宾补,而在被动句中需把省去的to补出。
★考题回放                                
(    )4. You are so busy. What do you want me ______ for you?
A. do    B. done    C. to do    D. doing
(    )5. Jane likes singing. We often hear her ______ after class.
A. sing    B. to sing    C. sings    D. sang
(    )6. Colors can change our moods and make us ______ happy or sad, energetic or sleepy.
A. to feel   B. feeling    C. felt     D. feel
(    )7. Some children are made ______ a lot of homework after school.
A. do    B. doing    C. to do    D. done
四、动词不定式作定语。动词不定式作定语时,通常放在所修饰的词之后。如果动词不定式中的动词是不及物动词,有时需补出一个介词意思才完整。★考题回放                                
(    )8. They had no room _______.
A. to live   B. to live in   C. living    D. living in
五、动词不定式作状语。动词不定式作状语时,表目的的情况较多,也可表结果等。
★考题回放                                
(    )9. I stayed there ______ what would happen.
A. to see    B. seeing    C. saw     D. seen
(    )10. —Have you finished the English story book?
—Not yet. It’s too hard _____.
A. understand     B. understanding  
C. to understand     D. understood
六、带有逻辑主语的动词不定式复合结构。动词不定式的逻辑主语一般由介词for引出,但在某些具有评价人物品行意味的形容词(如:kind,nice,good,careful,careless,foolish,clever,selfish,rude,right,wrong,brave等)之后常由介词of引出。
★考题回放                                
(    )11. It’s important ______ the piano well.
A. of him to play     B. for him to play  
C. of him playing     D. for him playing
(    )12. It’s wrong ______ her like that.
A. of you to treat     B. for you to treat  
C. of you treating     D. for you treating
七、动词不定式的否定形式。动词不定式的否定形式是在to前直接加not或never。
★考题回放                                
(    )13. There are some dangerous fishes in this river, and I’ve warned Jack _____ in it.
A. not to swim     B. to not swim  
C. swim not to     D. to swim not
八、“疑问词+动词不定式”结构。“疑问词+动词不定式”结构常可与从句互相转换,疑问词的选用需根据句意来确定。
★考题回放                                
(    )14. —I don’t know _____ to open the bottle.
—You can put it in hot water for a few minutes.
A. which    B. what    C. how     D. why
(    )15. —Are you going to buy a camera?
—Yes. But there are so many kinds that I can’t decide _____ to buy.
A. what     B. which    C. how     D. where

Key: 1-5 BDBCA   6-10 DCBAC   11-15 BAACB