Giúp mik với, mình cảm ơn ạ

=>
1. A at this time last week -> thì QKTD
2. C while QKTD, QKTD
3. C this is the second time -> HTHT
4. C this weekend -> HTTD
5. B often -> HTĐ
6. A QKHT by the time QKĐ
7. A used to : đã từng

8. B had to (QKĐ, have to -> had to)
9. C everyday -> HTĐ/ today -> HTTD
10. C yesterday -> QKĐ/QKHT diễn tả hành động xảy ra trước một hành động khác trong quá khứ)
11. C by the time QKĐ, QKHTTD
12. B vế trước là QKĐ
13. A QKTD when QKĐ

14. A in the 19th century -> QKĐ
15. were not doing/was cooking/was reading ( last night at this time -> QKTD)
16. arrived/discovered/was preparing (last night -> QKĐ)