1.the mouse's teeth are sharp(变一般疑问句并作肯定回答)
Are the mouse's teeth sharp?
Yes,they are.
2.its branches are long(意思不变改否定句）
Its branches aren't short.
3.she is always a good student 该为一般疑问句,作否定回答
Is she always a good studen?
No,she isn't.
不明白的再问哟,请及时采纳,多谢!谢了带 be动词，如果改一般疑问句一般只需把 be动词提前到句首