1/ No, he isn't. He's watching television.
2/ No, I'm not. I'm learning them by heart.
3/ No, he isn't. He's reading a newspaper.
4/ No, they are not. They are talking with a friend.
5/ No, I'm not. I'm going home.
6/ No, he isn't. He's listening to a concert.
7/ No, I'm not. I'm writing a film script.
8/ No, she isn't. She's cooking.