大家好，我是小环，我来为大家解答以上问题。肯定句变否定句20道题及答案，肯定句变否定句很多人还不知道，现在让我们一起来看看吧！

1、用实际例子给你说明吧 1. I think she is there. 误：I think she isn’t there. 正：I don’t think she is there. 析：英语中think, believe, expect, suppose等表示信念和揣测的动词，后接that从句时，习惯上将从句中的否定形式转移到主句上，即否定主句谓语，不否定从句谓语。

2、 2. He can sing this song and that one. 误：He cannot sing this song and that one. 正；He cannot sing this song or that one. 析：肯定句中的连词and在否定句中一般要改为or。

3、 3. Tom went to school too. 误：Tom didn’t go to school too. 正：Tom didn’t go to school either. 析：too和also用于肯定句中时，否定句中用either替换。

4、 4. He has had supper already. 误：He hasn’t had supper already. 正：He hasn’t had supper yet. 析：随着对谓语动词的否定，某些副词也要作相应的变动。

5、 5. He had a good rest just now. 误：He hadn’t a good rest just now. 正：He didn’t have a good rest just now. 析：have在表示开会、吃饭、休息、进行体育锻炼等词组中是行为动词，否定句用助动词来完成。

6、 6. Let’s do it. 误：Let’s don’t do it. 正：Don’t let’s do it.或Let’s not do it. 析：let后接的是不带to的不定式，变为否定式，直接在句首前加Don’t或在不定式前加not。

7、 7. He always gets there on time. 误：He doesn’t always get there on time. 正：He never gets there on time. 析：He doesn’t always get there on time意为“他并非老是准时到那儿”，是部分否定，习惯上把句中的副词改为相应的表示否定的副词即可。

8、如： It often rains here. It seldom rains here. 8. Be here early tomorrow. 误：Be not here early tomorrow. 正：Don’t be here early tomorrow. 析：祈使句的否定，一般在谓语动词前加do not的缩写don’t。

9、 9. You had better come. 误：You didn’t have better come. 正：You had better not come. 析：had better相当于一情态动词，不可分割，因此not应放在其后。

10、would rather也是如此。

11、 10. Both Tom and Xiao Ping went to school. 误：Both Tom and Xiao Ping didn’t go to school. 正：Neither Tom nor Xiao Ping went to school. 析：一个句子中如果有不定代词both，all, every改为否定式时，要把这些不定代词改为相应的表示否定的代词。

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