№ 3
1. sitting
2.studying
3.working
4.eating
5.having
№ 4
1)We aren't sitting 2) isn't studying 3) am not working 4) are not earthing 5) is not having
№5
1. Are you doing a test? Yes, I am.
2. Is your teacher sleeping? No, he isn't.
3. Are your friends studying? Yes, they are.
4. Is it raining today? No, it isn't.
5. Are your classmates singing? Yes, they are.
6. Is your dad working. No, he isn't.