英语肯定句变否定句所有规则21

一、简单句中含有be动词、情态动词和助动词时，变否定句

时需在be动词、情态动词和助动词后加not。

1. （am, is ,are 是be动词）如：I am a teacher．→I am not

a teacher．This is a pen.→ This is not a pen.或This isn’t a pen. (is not =isn’t) You are a boy. →You are not a boy. (are not =aren’t)

2. （can是情态动词）He can help me．→He can not help me．或He can’t help me.(can not =can’t )

3.当主语是第一人称、第二人称和第三人称复数时用助动词do,变否定时，在do后面加not 如：I like English .I do not like English.或I don’t like English.

They go to school together. →They do not (don’t) go to school together.

4.当主语是第三人称单数时用does,变否定时，在does后面加not，如：The little girl wants to go there.→ The little girl does not (doesn't ) want to go there．

2．简单句中谓语动词为行为动词时，要根据时态选用do的相应形式，把肯定句变为否定句。如：

The little girl wants to go there．→The little girl doesn't want to go there．

He did his work yesterday．→He didn't do his work

yesterday．

3．祈使句变否定句时，一般在句首加Don't，但Let us或Let's 开头的祈使句在Let us或Let's后加not也可。如：

Put them over there．→Don't put them over there．

Let us go home．→Let us not go home．

或Don’t let us go home.

4．主从复合句中，主句是I think，I believe等结构，变否定句时，形式上否定主句，实际上否定从句。如：

I don't think chickens can swim ．我认为鸡不会游泳。5．“had better＋动词原形”，变否定句时为“had better not ＋动词原形”。如：

You'd better go to school．→ You'd better not go to school．6．动词不定式变否定式时，常在不定式to前加not。如：The teacher tells me to do it．→ The teacher tells me not to do it．

7．使役动词和感官动词（make，let，hear，see，watch等）后接省略to的不定式，此种不定式变否定句时只需在省略to 的动词原形前加not。如：

I saw her work．→I saw her not work．

8．特殊形式的否定句，有以下几种：

（1）肯定句含有every-的合成词时，变否定句时改为no-。如：

Everything is ready．→Nothing is ready．

（2）肯定句中含有always，usually和ever时，变否定句时改为never。如：

He is always late for school．→He is never late for school．（3）肯定句含有many，much时，变否定句时分别改为few，little。如：

Many students know him．→Few students know him．

（4）肯定句中含有still时，变否定句时应改为no longer。如：Tom is still in bed．→Tom is no longer in bed．

（5）肯定句含有both，both．．．and，all时，变否定句时应改为never，neither．．．nor，none。如：

Both of us are students．→Neither of us is a student．

（6）肯定句含有nearly，almost时，变否定句时应改为hardly。如：

Lily nearly knows him ．→Lily hardly knows him ．

（7）肯定句含有“形容词＋enough”时，变为否定句时应改为“too ＋形容词的反义词”。如：

He is short enough to reachit．He is too tall to reach it．（1）谓语动词是be，have（有）或谓语含有助动词、情态动词时，直接在这些词后加上否定词not。如：

She can swim．She can't swim．

（2）谓语动词是行为动词时，要在该动词前加上do ／does

／did not，该词恢复原形。如：

He gets up early．He doesn't get up early．

（3）既要否定谓语动词，又要变换句中的单词。如：

He can read and write．He can't read or write．

（4）用含否定意义的词或词组取代肯定句中的某些词或词组。如：

I know both English and Chi- nese．I know neither English nor Chinese．

类似的有：ever ／always never，somebody nobody，something nothing，everybody no one，almost hardly 2．祈使句的肯定式变否定式

（1）一般在动词前加上don't。如：

Open the window ．Don't open the window．

（2）含有“L et's．．．”的祈使句，一般用“Let'snot．．．”的形式，美国人偶尔也用“Don'tlet's．．．”这一形式。加强语气时使用“Let'sdon't．．．”这一形式。如：

Let's go there．Let's not go there．

3．复合句的肯定式变否定式

一般将主句变为否定式。如：I saw her when I left ．I didn't see her when I left．

肯定句改为否定句的基本方法