1. 否定陈述句形式：
　a. 谓语是特殊动词 be，have，助动词或情态动词等，或含有特殊动词时，直接在特
　　殊动词后加 not 构成，如：
　　　Mr. Smith is not a lawyer.
　　　She hasn't much money left.
　　　My sister will not come here this summer vacation.

　b. 谓语是普通动词时，则在谓语动词前加助动词 do (does, did)，然后加 not 构成，
　　如：
　　　This coat doesn't fit me.

　c. 含有两个以上特殊动词时，则在第一个后加 not 构成；但注意一些半助动词的否
　　定形式是 had better not, had rather not, had sooner not，如：
　　　You should not have told him.
　　　You'd better not go out today.

　d. 在回答 Will he go with us tomorrow? 这类句子时，可以说 I think (believe,
　　expect, suppose, fear, am afraid, should say, etc.) not，这里的 not 代替从句
　　that he will not go with us tomorrow 在句中作宾语，通常不把它看成谓语动词的
　　否定形式。

2． 否定疑问句形式：通常是把 not 放在主语后构成，但口语里通常放在主语前和特殊动
　　词构成缩略式，如：
　　　Can he not make a decision? / Can't he make a decision?
　　　Did he not go there? / Didn't he go there?

3． 祈使句否定形式：Don't (never) + 不带 to 的不定式；带 let 的 祈使句，直接用 not 等
　　否定词构成，如：
　　　Don't be so careless.
　　　Don't switch off the light.
　　　Never tell a lie.
　　　Let's not do what is wrong.