否定句

否定句

否定句是陈述句的一种形式，对人对事总是持有否定的态度，和肯定句唱反调，常在肯定句加上"不"字，具体如下：

1. 结构: 主语＋be 动词（am／are／is／was／were）＋not＋…

说明: 当句子中有ｂｅ动词时，只需在肯定句中be <动词>的后面加not 就构成<否定句>。例如：

I am a student.→I am not a student.

We were at home yesterday.→We were not at home yesterday.

There are some apples in the box. →There aren’t any apples in the box.

２. 结构: 主语＋情态动词（can, must等）＋ｎｏｔ＋．．．

说明: 当句子中有情态动词时，只需在肯定句中情态动词后面加not就构成<否定句>。例如：

He’ll go to Beijing tomorrow. →He won’t go to Beijing tomorrow.

The baby can walk and speak. →The baby can’t walk or speak.

3. 结构: 主词＋don’t／doesn’t/didn’t＋原形动词＋…。

说明: 当句中没be动词也没情态动词时，肯定句变否定句，则在实义动词前加don’t / doesn’t/didn’t,再把实义动词还原，即构成<否定句>。例如：

I have some brothers.→I don’t have any brothers.

My mother speaks English.→ My mother doesn’t speak English.

4. 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即可。如：

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

Let us go home．→Let us not go home．

5. 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 think chickens can swim. →I don't think chickens can swim ．

6. “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．

7. 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．

8. （1）当肯定句的谓语动词是have，表示有什么，改为否定句的方法有三种：(A) 由have＋not＋其他; (B)由have 十no 十其他；(C)由don't（doesn't，didn't）＋have 十其他。如：

I have some story books. →I haven’t any story books./I have no story books./

I don’t have any story books.

（2）当肯定句的谓语由have 十其他词构成，这时have 不当“有”讲，也不是“助动词” ，改为否定句时，由助动词( do/does/did）＋not＋have 构成否定结构。如：

They have breakfast at seven．→They don’t have breakfast at seven.

9. 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＋名词或者both of＋名词作主语时，改为否定句时则用neither代替both，并且要注意谓语动词数的变化。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 tall enough to reach it．→He is too short to reach it．

注意：1）有some要改为any, 但固定搭配如do some reading, do some shopping ,do some cooking等不用改. 2）有too，also要改为either; and 要改为or; already改为yet.

把下列句子改为否定句

基本题：

1. There is a book on the desk.

______ ______ a book on the desk.

2. We are going to swim.

_____ ______ going to swim.

3. He is playing with the toy.

____ ____ playing with the toy.

4. She’s a nurse.

_____ _____ a nurse.

5. There are some pigs under the tree.

_____ _____ _____ pigs under the tree.

6. They walk to school.

_____ _____ _____ to school.

7. Janet is 10 years old.

____ _____ 10 years old.

8. I am doing my homework.

_____ ______ doing my homework.

9. The girls are doing their homework.

____ _____ _____ doing their homework .

10. Ben is from America.

_____ _____ ____ from America.