肯定句变否定句的基本方法

1、.肯定句变否定句的基本方法一、动词 be 的否定式 动词be根据不同的人称和时态可以有am, is, are, was, were等不同形式，可用作连系动词(表示“是”、“在”等)和助动词(用于构成进行时态和被动语态等)，但不管何种情况，构成否定式时，一律在其后加notIm old, but youre young. 我老了，但你还年轻。Im not old, but youre not young. 我还不老，但你不年轻了。He was reading and I was writing. 他在读，我在写。He was not reading and I was not writing. 他

2、没有在读，我没有在写。 二、 动词 have 的否定式 动词have根据不同的人称和时态可以有have, has, had等形式，可以用作实意动词和助动词，分以下情况讨论1. 用作实意动词表示状态，如表示拥有、患病或用于have to表示“必须”等，在构成否定式时可以直接在其后加not，也可根据情况在其前使用dont, doesnt, didntHe has a car. 他有辆小汽车。He hasnt a car. / He doesnt have a car. 他没有小汽车。He had some dictionaries. 他有一些词典。He hadnt any dictionaries

3、. / He didnt have any dictionaries. 他没有词典。You have to go with him. 你必须同他一起去。You havent to go with him. / You dont have to go with him. 你不必同他一起去。【注】have to构成否定式时以在其前加dont等较为常见。2. 用作实意动词表示动作，如表示“吃(=eat)”、“喝(=drink)”、“拿(=take)”、“收到(=receive)”、“度过(=spend)”等，构成否定式时不能直接在其后加not，而应根据情况在其前使用dont, doesnt, did

4、ntHe had some cake for breakfast. 他早餐吃了些蛋糕。He didnt have any cake for breakfast. 他早餐没有吃蛋糕。(不能用had not)We had a good holiday. 我们的假期过得很愉快。We didnt have a good holiday. 我们的假期过得不愉快。(不能用had not)3. 用作助动词构成完成时态，其否定式只能在其后加notI have read the book. 我读这本书。I have not read the book. 我还没读这本书。He had left when I ar

5、rived. 我到达时他已离开了。He hadnt left when I arrived. 我到达时他还没有离开。 三、情态动词的否定式 情态动词的否定式一般在其后加not构成I can finish the work in an hour. 我能在1小时内完成这工作。I cant finish the work in an hour. 我不能在1小时内完成这工作。You must go with us. 你必须同我们一起去。You mustnt go with us. 你不能同我们一起去。We should help them. 我们应该帮助他们。We shouldnt help them

6、. 我们不必帮助他们。 四、实意动词的否定式 一般实意动词的否定式，通常应根据不同时态和人称在实意动词之前加dont, doesnt, didnt等He works in a bank. 他在一家银行工作。He doesnt work in a bank. 他不是在银行工作。We often hear from her. 我们经常收到她的来信。We dont often hear from her. 我们不经常收到她的来信。I met her at the station. 我在车站见到了她。I didnt meet her at the station. 我在车站没见到她。要注意加上does

7、 not或did not改为否定句以后，要把原句的动词改为原形动词，特别是行为动词do的第三人称单数does和过去时did，在主语后面加上doesnt或didnt以后，千万要注意把句中的does或did改为 do。五、祈使句的否定结构为：dont十原形动词。改为否定句时，要在句首加上dont，其它不变，即：Look out of the windowDont look out of the window六、当陈述句中含有something这个词时，把句子改为否定句有两种方法：其一，在句中相应位置加not，再把something改成anything；其二，直接把something改为nothin

8、g即可。例There is something wrong with the radio把这个句子改为否定句有两种方法：其一，先把not加在is后面，再把something改为anything即：There is not anything wrong with the radio其二把something直接改为 nothing，即：There is nothing wrong with the radio例.I have something important to tell you .把这个句子变成否定句有两种方法：其中一种方法是先把not加在have后面，再把something变成anyt

9、hing，即：I have not anything important to tell you第二种方法是直接把something改为nothing，即：I have nothing important to tell you七、当陈述句是一个主从复合句，而主句的谓语动词是think或believe等时，把这种句子改为否定句，往往是否定think或believe等而不否定后面从句中的谓语动词，尽管意思是否定从句的谓语动词。例I think he will be back soon这个复合句中主句的谓语动词是think，所以在改为否定句时要在think前面加上 dont，即：I dont th

10、ink he will be back soon汉语意思：我认为他不会很快回来。八、某些特殊句型改为否定句时，有不同的方法：1）在陈述句中含有had better时，要把 not加在better后面，动词原形前面。例You had better go with us把这个句子改为否定句，要把not加在 better之后，g o之前，即：You had better not go with us千万不要改成：You had not better to go with us或You had better dont go with us因为，要否定的是后面的动词不定式短语。同时，had better

11、后面要用动词原形（不带 to）。2）当陈述句中含有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。例Both of them work in the school library句子含有both，改为否定句时用neither代替both，同时谓语动词work改为works，即：Neither of them works in the school library例Both answers are right把这个句子改为否定句，用neither代替 both，谓语动词are改为is，即：Neither answer is ri

12、ght3）句中含有bothand的肯定句改为否定句时用neither nor改写，同时neithernor还可以把两个简单句的否定形式连成一个句子。例Both Mary and Joan are students把这个句子改为否定句时，通常用Neithernor代替Bothand，同时把are改为is，students改为a student即：Neither Mary nor Joan is a studentneithernor连接两个主语时，谓语动词决定于nor后面的名词或代词的单复数形式。例This book is both interesting and instructive把这个句

13、子改为否定句，用neithernor代替bothand，因为连接部分在句中作表语，所以谓语动词不变，即：This book is neither interesting nor instructive例I dont see that filmHe doesnt see it either这两个否定句可以用neithernor连成一个句子，谓语动词改为肯定式see，人称和数由nor后面的he决定，即：Neither he nor I see that film ，或者把I和he交换即：Neither I nor he sees that film这说明谓语的人称和数由nor后面的靠近谓语的人称和

14、数决定。在把肯定句改为否定句时，注意把句中的 some，already，something等词改为any， yet，anything。有一些表示否定意义的副词，如never， seldom ，hardly ，little ，few等也可以使句子成为否定句。例如：He has few good friends hereThere is little water in the bottleI hardly believe it巩固练习：将下列句子改为否定句1We do morning exercises every day We _ _ morning exercises every day2Al

15、l of us can swim _ _ _ can swim _ Joan _ I _ in Class One4There is something wrong with my bike There _ _ wrong with my bike5You may stay here before I come back You _ _ here before I come back6Read the text after me _ _ the text after me7Li Lei needs some help with his English Li Lei _ _ _ help with his English8He said he would g o to Beijing the next week He _ _ _ _ go to Beijing the next week9The bike has already been m ended