1.Are they doing housework?
Yes,they are./ No,they aren't.
They are not doing housework.
2.Are the students cleaning the classroom?
Yes,they are./ No,they aren't.
划线部分是哪个?
3.Are you playing the football in the playground?
Yes,they are./ No,they aren't.
划线部分?
4.Is Tom reading books in his study?
Yes,they are./ No,they aren't.
划线部分?