Mấy bn giúp m mấy câu này vs

=>

19. D (QKHT by the time QKĐ)

20. D by the age of 25 -> QKHT

21. B (QKĐ, S V2/ed)

22. C (QKHT)

23. C this is the first time + HTHT

24. B since + QKĐ

25. B after QKHT, QKĐ

26. B (QKĐ, S V2/ed)

27. B QKĐ when QKTD

`#Hmy`

19 . D . had left

DHNB QKHT : Diễn tả `1` hđ x.ra trc `1` hđ / `1` thời điểm trg QK .

20. D . had written

QKHT : By + mốc tg trg QK , S + had + V2

21 . B . wrote

When + S + V2 , S + V2 ( mđề TN chỉ tg )

22 . C had broken down

a few day presiously : QKHT

23 . C . have tried

It's the first time S + V : HTHT

24. B . he left

Since + S + V2 , S + have + V2

25 . B . had had

After + S + had + V3 , S + V2

26 . B . walked
`3` hđ diễn ra liên tiếp trg QK

27.  B . went

`1` hđ đang x.ra trg QK thì hđ khác xen vào 

* Hđ xen vào chia QKĐ