3、及练习 （一）Be型 (be+adj) Be careful! Be dangerous! Be quiet! （二）Do型 (Do代表动词原形) Open the door! Close the window! Go and play football! （三）Let's或Let us型 Let's go home! Let us help Mary! Let me clean the room! （四）No+动名词，多用在标语禁令中 No smoking! No parking! No spitting! No+动名词可以与Don't+动词原形替
4、换。 No smoking!=Don't smoke! 三、否定形式 Be型和Do型前直接加Don't， Let's型可前面直接加Don't或let's后加not。 Don't be careful! Don't open the door! Don't let's go home!/Let's not go home! 四、反意疑问句 祈使句的反意疑问句一般用will you? Let's---用shall we? Let us---用will you? Open the door,will you? Let's go home,shall w
5、e? Let us help Mary,will you? ②练习：（一）用括号内所给词的适当形式填空 1． It's an important meeting.______ (not be) late.2．_____ (look) out!A car is coming! 3．________ (not make) any noise! The baby is sleeping. 4．Let's _______(not say) anything about it. 5．________ (not let) the baby cry. 6．___
6、__ (read) aloud,please. 7．_________ (not talk) with your classmate in the class. （二）选择题 1．Her doctor said:"____ work so hard" A. stop B. Don't C. can't D. No 2．Sindy,____ to be here at 8 o'clock. A. is sure B. is sure that C. will be sure D. be sure 3．_____ him the sec
7、ret,will you? A. Don't tell B. Not to tell C. Not telling D. No telling 4．Please _____ look outside,look at the blackboard. A. not B. don't C. aren't D. can't 5．John,read the text for us,_____ ? A. does he B. will he C. do you D. will you 6．Let's do it at once,__
8、___ ? A. shall we B. will you C. do we D. do you
