1 bought ( thì QK)
2 were ( cấu trúc mong ước QK)
3 playing (used to +V-ing)
4 Have....had thì HTHT( have -had-had)
5 built thì QK ( build-built-built)
6 Did...see (thì QK)
7 knew ( cấu trúc mong ước QK)
8 haven't seen thì HTHT (see-saw-seen)
Cho mk ctlhn nhó !
@Ngoclinh