动词不定式可以充当________以外的所有成份；不定式作主语或宾语时，常用________形式主语或形式宾语；在see, hear, watch, feel, notice, observe, make, let, have, listen to, look at等词后的补足语中，不定式不带to，但是这些句子如果变成被动结构，就必须带________；动词不定式在介词________，________，________后面时，如果这些介词之前有行为动词do的各种形式，那么，这些介词后的不定式不带to，否则要带to。

选词填空

turn back往回走，使…倒转　　turn down把(收音机等)开小一些

turn in上交，上床睡觉　　turn on开(收音机，灯等)

turn off关(收音机，灯等)

turn out生产，制造(成品)或跟不定式，构成复合谓语，跟从句(用it作主语)其后跟形容词、副词、名词、意为结果，原来(情况)

turn over移交，翻阅，考虑，细想　　turn to向…求助，翻到

turn up出现，来(开会，赴约等)(把收音机)开大一点声

(1)To whom should we ________ the key when we leave the room?

(2)“Please ________ page 40,”said the teacher．

(3)He promised to attend my birthday party, but till now he hasn’t ________ yet．

(4)Excuse me, ________ the radio a little．I could hear nothing．

(5)If you have any difficulty, you can ________ me．

(6)That radio is pretty loud．Could you ________ it ________ a little?

(7)I want to ________ early tonight because I should get up early tomorrow．

(8)Remember to ________ all the lights before you leave the room．

(9)Have you ________ your exercise book?

(10)The wheel of history can never be ________．

(11)Would you mind ________ the light?It is dark．

(12)She was afraid things were not going to ________ smooth for us．

(13)The English evening party ________ a great success．

(14)The factory ________ 2000 new cars last year．

(15)It ________ that he has never been there．No wonder he knows nothing about it．