注意：
在肯定句中的some变成否定句时要变成any。 例如：We have some books. We don't have any books. There are some birds in the tree. There aren't any birds in the tree.
把下列句子变成否定句。
肯定句变成否,is,are)动词：
变否定句直接在be(am,is,are)词后加not。 如：am not, is not, are not; 例如：I am a teacher. I am not a teacher. She is tall and thin. She isn't tall and thin. They are students. They aren't students.
Thank
you!
1.I'm a student. 2.Your father can ride a bike. 3.There are some books in the bookcase. 4.We come from China. 5.He likes the violin. 6.Have some bread ,Tom. 7.Tom and Mary are friends. 8.His mother is a farmer. 9.They can play football after school. 10.She has some storybooks.
3、如果没有be动词和情态动词的：
句子是一般现在时的，如果主语是第一、二人称和第三人称 复数形式，或者主语是复数的，变否定句是在动词前面加助动词的 否定形式（don't)。 例如：I like red. I don't like red. You have a new bike. You don't have a new bike. They like storybooks. They don't like storybooks. The boys play football on the playground. The boys don't play football on the playground.
2、如果句子中含有情态动词 （can,should,will等)的:
变否定句时直接在情态动词(can,should,will)后加 not。 如：can not,should not, will not; 例如：He can swim. He can't swim. I will go to park tomorrow. I will not go to park tomorrow.
答案：
1.I'm not a student. 2.Your father can't ride a bike. 3.There aren't any books in the bookcase. 4.We don't come from China. 5.He doesn't like the violin. 6.Don't have any bread ,Tom. 7.Tom and Mary aren't friends. 8.His mother isn't a farmer. 9.They can 't play football after school. 10.She doesn't have any storybooks.
在一般现在时中，如果主语是第三人称单数 （he,she,it)或者人名时，变否定句是在动词前面加 上助动词的否定形式（doesn't),并且动词变回原形。
例如：He has a new pen. He doesn't have a new pen . She reads books every day. She doesn't read books every day. It wants to eat meat. It doesn't want to eat meat. Mary goes to school on foot. Mary doesn't go to school on foot.