Ex 6: 1, Have/ finished
2, Did/ see
3, have never done
4, Have/ ever broken
5, Did/ play
6, Have/ ever eaten
7, Have/ posted
8, did/ learn
Ex 7: 1, started
2, worked
3, spent
4, did/ get
5, studied?
6, had
7, helped
8, was
9, did/ join
10, have/ done
11, signed up
12, haven't got
13, cycle

6. 1, Have you finish                               5, Did you play
    2, Did you see                                     6, Have you ever eat
    3, I have never do                               7, Have you posted
    4, Have you ever broken                     8, What did you learn 
7. Mk vẫn chưa hiểu lắm đề bài bài này.