`1.` He sent an email to his boss before taking a day off.

`2.` He had been able to save a lot of money before he had an early retirement.

`3.` He had briefed us about the new year’s objectives before we met the clients.

`4.` The lights went off after we had left the office.

`5.` Had you brought the package to the post office before you came here?

`6.` She called the police after she had felt the presence of someone in her house.

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`-` QKHT + before + QKĐ/V-ing

`->` Diễn tả hành động quá khứ này xảy ra trước 1 hành động quá khứ khác. ( hành động xảy ra trước chia QKHT, hành động xảy ra sau chia QKĐ)

`-` QKHT:

(+) S+ had+ V-pp+O

(-) S+ had+not+V-pp+O

(?) Had + S+ V-pp +O?

Wh-words + had+SV-pp+O?

`color{pink}{Vanie}`

`1`. He sent an email to his boss before taking a day off.

`2`. He had been able to save a lot of money before he had an early retirement.

`3`. Before meeting the clients, he had briefed us about the new year’s objectives.

`4`. The lights went off after we had left the office.

`5`. Had you brought the package to the post office before you came here?

`6`. She called the police after she had felt the presence of someone in her house.

_______________________________________________________________________________

Công thức thì quá khứ đơn

(`+`) S + V-ed + ...

(`−`) S + didn't + V-inf

( `?` ) Did + S + V-inf .... ?

`***` Dấu hiệu nhận biết: Yesterday, ago, last,...

`+` Khoảng thời gian trong quá khứ

Thì quá khứ hoàn thành

(`+`) S + had + V-p 3

(`−`) S + had + not + V- 3

( `?` ) Had + S + V-p 3 ...?

`***` Dấu hiệu nhận biết: for, since, yet, already,...