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：

(1) He is there. ― He is not there. 他不在那儿。

(2) I have finished my work. ― I have not finished my work. 我的工作还没完成。

(3) She will agree with you. ― She will not agree with you. 她不会同意你的意见。

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。

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。

3. 对于不含系动词be、助动词或情态动词的句子，则在谓语动词前加do not的适当形式, 同时将原谓语动词改为原形。如：

(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。