2．句子按功能分可分为陈述句、疑问句、祈使句和感叹句

　　　　 陈述句用来说明一件事实或表达一种看法；疑问句用来提出问题；祈使句用来发出请求或命令；感叹句用来表达强烈的感情。

1．句子按结构分可分为简单句、并列句和复合句

　　　　 简单句只有一个主语(或并列主语)和一个谓语动词(或并列谓语动词)。例如：

He likes swimming and often swims in the river. 　　 并列句由并列连词把两个或两个以上简单句连在一起构成。例如：

　　　　　 I learn English and he learns French.

　　　　 复合句中含有一个或一个以上的从句。例如：

　　　　　 It was raining hard when I got home yesterday.

II、

2.must　　　 5.Shall　 6.dare　 7.have　 8.need　 9.Dare　’t

15.Certain species of birds ________ find food because of pollution.

　　　　 A. mustn’t　 B. shouldn’t　 C. cannot　 D. couldn’t

I、

14.He promised that he ________ help us as long as we needed.

　　　　 A. must　 B. had to　 C. would　 D. should

13.Your shirt is rather dirty. ________ I wash it for you ?

　　　 A. Do　 　B. Will 　C. Have　 　D. Shall

12.The food must be good. No, it ________ be good.

　　　 A. must not　 　　　　B. needn't

　　　 C. wouldn't 　　　　　D. cannot

11.Hurry up. He ________ for us at the station.

　　　 A. must wait　　　　 B. must be waiting

　　　 C. should wait 　　　D. should be waiting

9.You ________ return the book now. You can keep it till next week.

A. can't 　B. mustn't　 C. needn't 　D. may not

(　 ) I leave this door open at night ? No, you ________ .

A. should better not 　B. would better not

C. had better not　　　 D. mustn’t better