含有be动词和情态动词的句子,怎么变否定句和一般疑问句

问题描述:

含有be动词和情态动词的句子,怎么变否定句和一般疑问句
快,急用

举最简单的例子
(1)You are(be) a student.
否You are not a student.
问Are you a student?
(2)You can do it.
否You can not do it.
问Can you do it?