11. have been (HTHT; dấu hiệu: since)
12. haven’t seen (HTHT; dấu hiệu: lately)
13. Has there been (HTHT; dấu hiệu: since)
14. have never seen (HTHT; dấu hiệu: never)
15. have ever read (Thì HTHT)
16. has seen (HTHT; dấu hiệu: since)
17. have seen (thì HTHT)
18. have met (HTHT; dấu hiệu: It is the first time)
19. was (QKĐ; dấu hiệu: yesterday)
20. haven’t lived (HTHT; dấu hiệu: for two years now)