6. Went(QKĐ) / hadn't enjoyed (QKHT)
7. Was doing (QKTD) / met (QKĐ)
8. Noticed (QKĐ) / is (HTĐ)
9. Have (HTĐ) / had had (QKHT)
10. Am revising (HTTD)
11. Have already begun (HTHT)
12. Think (HTĐ) / will do (TLĐ)
13. Is (HTĐ) / won't (TLĐ)
14. Pass (HTĐ) / will start (TLĐ)