英语句型转换之一
——肯定句变否定句的技巧
请同学们记住以下单词：
1、be动词的五种形式：am, is, are, was, were；
2、情态动词：can, could, may, might, must, shall, should,
will,would, need, had better
3、助动词：have, has, had
一、动词后直接加not
原句中含有be动词(am, is, are, was, were) 和情态动词(can, shall, will, may, should, would, might, had better等)时，要在动词后直接加not。如：
1. I am a teacher. →I am not a teacher.
2. Li Lei can swim. →Li Lei cannot（can't ）swim.
3. He will go to the zoo if it rains tomorrow.
→He will not（won't）go to the zoo if it rains tomorrow.
4. We have learned 3,000 words.
→We have not（haven't ）learned 3,000 words.
二、原句中没有be动词，助动词或情态动词时，要在行为动词前加助动词(do, does, did)与否定副词not的缩写形式。
1. 句中第一个动词是原形时，在其前加上don’t。如：
I get up at six o'clock every day.
→I don't get up at six o'clock every day.
2. 句中第一个动词是三单形式时，在其前加上doesn’t，原来的动词三单形式改为动词原形。如：
Mr Wang works in a factory.
→Mr Wang doesn't work in a factory.
3. 句中第一个动词是过去式时，在其前加上didn’t，原来的动词过去式改为动词原形。如：
Xia Lin visited our friends last night.
→Xia Lin didn't visit our friends last night.
三、肯定句变否定句的七点注意
1. 肯定句变否定句时，除将谓语变为否定式外，句中其他词语也可能随之改变，如将some改为any，too和also改为either，already 改为yet，and改为or等。如：
There are some birds in the tree. 树上有些鸟。
→There aren’t any birds in the tree. 树上没有鸟。
He likes the girl, too. 他也喜欢这个女孩。
→He doesn’t like the girl, either. 他也不喜欢这个女孩。
We have already seen the film. 我们已看过这部电影。
→We have not seen the film yet. 我们没有看这部电影。
He likes singing and dancing. 他喜欢唱歌和跳舞。
→He doesn’t like singing or dancing. 他不喜欢唱歌和跳舞。
2. 复合句的肯定式变否定式
a. 在含有宾语从句的主从复合句中，当主句的主语是第一人称，谓语动词是think, believe, guess时，如果要否定后面的宾语从句，习惯上否定主句的谓语动词。如：
I think he is 13 years old.
→I don't think he is 13 years old.
I believe she will come here soon.
→I don’t believe she will come here soon
b. 其他一般将主句变为否定式。如：
I was cooking when Mum got home.
→I was not cooking when Mum got home.
3. 不变谓语动词而变其他词语
a. 肯定句中含有both, both …and时，变否定句时both →neither；both …and→neither …nor；all→none。如：
Both of us are students. all→Neither of us is a student.
I know both English and Chinese.
→I know neither English nor Chinese.
All of them like bananas. →None of them like(s) bananas.
b. 肯定句中含有every-, some- 的合成词，变否定句时常改为含
有no- 的合成词。如：
Everything is ready. →Nothing is ready.
There is something wrong with my bike.
→There is nothing wrong with my bike.
c. 肯定句中含有“形容词＋enough to do sth.”，变否定句时改为“too ＋形容词的反义词＋to do sth.”。如：
She is old enough to go to school.
→She is too young to go to school.
d. 肯定句中含有always 和ever ，变否定句时改为never 。如：
He is always late for school. →He is never late for school.
My uncle's ever been to many parts of England.
→My uncle has never been to many parts of England.
4. 祈使句的肯定式变否定式
a. 一般情况下，在句首的动词前加Don't 。如：
Close the door. →Don't close the door.
b. 以Let's 或Let us 开头的祈使句，在变否定句时常在其后加not；有时也可在其前加Don't 。如：
Let me try again.
→Let me not try again.
→Don't let me try again.
5. 动词不定式变否定式时，常在不定式符号to 前加not 。如：
The teacher asked me to speak more loudly.
→The teacher asked me not to speak more loudly.
6. 部分否定与完全否定
比较以下句子：
All of us laughed when we heard it. 听到这事时我们都笑了。(肯定句)
All of us didn’t laugh when we heard it. 听到这事时我们并未都笑。(部分否定)
Not all of us laughed when we heard it. 听到这事时我们并未都笑。(部分否定)
