1.am
否定句：I'm not at home
疑问句：Are you at home?
2.studied
They didn't study English last year.
Did they study English last year?
3.did
I didn't do homework yesterday.
Did you do homework yesterday?
不明白的再问哟,请及时采纳,多谢!肯定回答和否定回答也写1.Are you at home?Yes, I am.No, I'm not.2.Did they study English last year?Yes, they did.No, they didn't.3.Did you do homework yesterday?Yes, I did.No, I didn't.