英语句子按其使用目的可将其分类为：陈述句、疑问句、祈使句、感叹句。

陈述句(Declarative Sentence)是陈述一个事实或者说话人的看法的句子。它包括肯定句（The Affirmative Sentence）和否定句（The Negative Sentence）两种。陈述句在书写时句末用句号，在朗读时用降调。

陈述句的肯定式即肯定陈述句,它的谓语结构中不含否定词,例如

He is a student. 他是一个学生。

She lives in Nanjing. 她住在南京。

I can swin. 我会游泳。

Mr. Black will go to Beijing on business tomorrow. 布莱克先生明天将去北京出差。

Jane bought some new clothes yesterday. 珍妮昨天买了一些新衣服。

陈述句的否定式即否定陈述句,它的谓语结构中含有否定词如 not（不)，no(不,没有)， never(从不)， nothing(没有什么)，none 没有人)，few（几乎没有,后跟可数名词)， little(几乎没有,后跟不可数名词)，seldom(很少)，hardly(几乎不)等。例如：

He never goes to work late. 他上班从来不迟到。

This is not my bag. 这不是我的包

I can' t swin. 我不会游泳。

She didn' t find her book. 她没有找到她的书。

He won' t get up early tomorrow morning. 他明天早上将不会早起。

We have no school on Saturday or Sunday. 我们星期六和星期天不上学。

(1) 如果句子中有 be 动词(am,is,are,was,were)will或 shall、情态动词(can，could,must,need,may等)的时候,只需在这些词后面加 not，例如：

① My father is an engineer. 我父亲是一位工程师。 My father is not (=isnt) an engineer

② There were many shops near our school two years ago. 两年前我们学校附近有很多商店。 There were not (=weren't) many shops near our school two years ago

③ He can play Chinese chess very well. 他中国象棋下得很好。 He cannot(= can't) play Chinese chess very well.

④ I should go home at once, 我应该马上回家。 I should not(= shouldn’t) go home at once

⑤ He will walk the dog after supper. 他晚饭后将去遛狗。 He will not(= won’t) walk the dog after supper.

⑥ We shall have a sports meet next week. 下周我们将举行运动会。 We shall not (shan't) have a sports meet next week

注意：肯定句中的 some(一些),在改成否定句时,要把 some 改成 any,

(2) 如果句子中没有be动词助动词will或shall,情态动词,则要借助助动词don’t. doesnt或 didn’t,把它们放在主语的后面,再加上动词原形构成否定句，例如：

① I like listening to pop music. 我喜欢听流行音乐 I don't like listening to pop musIc,

② Sandy goes to school by bus every day. 桑迪每天乘公交车去上学 Sandy doesn t go to school by bus every day.