英语肯定句变否定句的基本方法

肯定句变否定句的基本方法

一、如果谓语中有情态动词、助动词或be，直接在它们后面加not构成否定句。

1.在含系动词be、助动词be, have, has, will, would, shall, should等之后直接加not，构成否定句。如：

He is there. — He is not there. 他不在那儿。

I have finished my work. — I have not finished my work. 我的工作还没完成。

She will agree with you. — She will not agree with you. 她不会同意你的意见。

He will not go there. 他不会那里。

I am not a teacher. 我不是教师。

2.否定含情态动词的句子：

a.在情态动词can, could, may, might, must, need, dare, had better, would rather的句子之后直接加not。如：

(1) He can say so. — He can not say so. 它不会那样说。

(2) Students must smoke. — Students must not smoke. 学生不允许抽烟。

(3)You’d better go there now.—You’d better not go there now. 现在你最好不要去那里。

(4)I’d rather tell you the truth.—I’d rather not tell you the truth. 我倒想不告诉你真相。

(5) He dared ask his parents for money again. — He dared not ask his parents for money again. 他不敢向父母亲要钱。

I can not dance. 我不会跳舞。

b.在含情态动词ought to的句子，在ought to中的to前面加not，构成否定句。如：

(1) You ought to bother him. — You ought not to bother him. 你不应该去麻烦他。

(2) You ought to waste your time. — You ought not to waste your time. 你不应该把时间浪费了。

c.在含情态动词used to的句子，可在used to中的to前面加not；也可在used前面加did not，同时将used 改为use。如：

(1) He used to smoke in the past . — He used not to smoke in the past. 他过去不常抽烟。

(2) He used to live here. — He did not use to live here. 他原来常不住这里。

d.在含情态动词have / has / had to的句子，在have / has / had to前面加do not的适当形式, 同时将has / had 改为have。如：

(1) You do have to stay here after school. — You do not have to stay here after school. 你不必放学后还呆在这里。

(2) He had to go to work yesterday. — He did not have to go to work yesterday. 他昨天不必去上班。

二、如果谓语中没有情态动词、助动词或be，在动词之前加do not (一般现在时第三人称单数用does not,过去时用 did not，并将原来的谓语动词改为原形) 。

(1) He likes classic music. — He does not like classic music. 他不喜欢古典音乐。

(2) She played table tennis yesterday afternoon. — She did not play table tennis yesterday afternoon. 她昨天下午没有打乒乓球。

You don’t look well today.你今天气色不好。

She does not know what to do. 她不知道做什么。

I didn’t do morning exercises today.我今天没做早操。

注：have做助动词时，在后面加not；作“有”解时也可以在后面加not；不是作“有”解的为行为动词时，其否定式和其他行为动词一样要在前面加do(does、did) not。如：

I haven’t finished my homework.我还没有做完作业。

I have not (=don’t have) a car.我没有汽车。

I don’t have lunch at school.我不是在学校吃中饭的。

She doesn’t have lunch at school.她不是在学校吃中饭的。

He didn’t have lunch yesterday.他昨天没有吃中饭。

注意：系动词be、助动词、情态动词的否定形式一般可以缩写成为一种简略的形式。如：is not—isn’t are not—aren’t

was not—wasn’t were not—weren’t

has not—hasn’t have not—haven’t

will not—won’t would not—wouldn’t

shall not—shan’t should not—shouldn’t

do not—don’t did not—didn’t

ought not—oughtn’t dare not—daren’t

used not to—usedn’t / didn’t use to