Here are the completed questions in the present continuous form along with the short answers:
Are you doing (do) your homework?
Yes, I am.Is your sister reading (read) a book?
No, she isn't.Is your uncle making (make) dinner?
Yes, he is.Are we having (have) sandwiches for lunch?
No, we aren't.Are my grandparents watching (watch) TV?
No, they aren't.Is the cat sleeping (sleep) on my bed?
Yes, it is.