1. They have done it early
1) They have done it early, haven't they?
2) Have they done it early?
3) Who has done it early?
4) Have we or they done it early?
5) What have they done early?
2. My friends went to Moscow last summer.
1) Did my friends go to Moscow last summer?
2) My friends went to Moscow last summer, didn't they?
3) Did my friends go to Moscow or to St Petersburg last summer?
4) When did my friends go to Moscow?
5) Who went to Moscow last summer?
3. They were happy.
1) Were they happy?
2) They were happy, weren't they?
3) Who was happy?
4) Were they happy or sad?
5) How did they feel?