they are playing footboll at school.改为否定句 i'm doing my homework now.改为一般疑问句,做否定回答the twins are singing in the room.对singing提问

问题描述:

they are playing footboll at school.改为否定句 i'm doing my homework now.改为一般疑问句,做否定回答
the twins are singing in the room.对singing提问

they are not playing footboll at school.
what are you doing, are you playing games? No, I am doing my homework.
What are the twins doing in the room?

They aren't playing football at school.
Are you doing your homework now? No, I'm not.
What are the twins doing in the room?