1. My dad is painting the house today.
2. A: What are you doing, Sam?
B: I am writing an email to my friend.
3. The children are not watching TV now. They are doing their homework.
4. A: Is John repairing his car?
B: Yes, he is.
Ответ: is painting; are ... doing, am writing; are not watching ... are doing; Is ... repairing.