`color{red}{#Atr}`

`1.` After David had gone, we arrived

`-` After + QKHT, QKĐ: Sau khi

`2.` Before we took a look around the shops, we had had lunch.

`-` Before + QKĐ, QKHT: Trước khi

`3.` When we got out of the office, the light had gone out.

`-` When + QKĐ, QKHT: Khi

`4.` By the time we started our work, she had explained everything dearly.

`-` By the time + QKĐ, QKHT: Trước khi

`5.` Before my mother came home, my father had watered all the plants in the gadern.

`-` Before + QKĐ, QKHT: Trước khi

`1`. After David had gone home, we arrived.

`2`. Before we took a look around the shops, we had had lunch.

`3`. When we got out of the office, the light had gone out.

`4`. By the time we started our work, she had explained everything clearly.

`5`. Before my mother came home, my father had watered all the plants in the garden.

`-----`

`***`

`-` After QKHT, QKĐ: Sau khi

`-` Before QKĐ, QKHT: Trước khi

`-` By the time QKĐ, QKHT: Vào lúc

`-` When QKĐ, QKHT: Khi

`->` Diễn tả một hành động diễn ra trước hoặc sau hành động khác trong quá khứ. Hành động diễn ra trước dùng QKHT, diễn ra sau dùng QKĐ.

`***` QKĐ:

`(+)` S + V2/ed

`(-)` S + didn't + V

`(?)` (Wh) + Did + S + V?

`***` QKHT:

`(+)` S + had + V3/ed

`(-)` S + hadn't + V3/ed

`(?)` (Wh) + Had + S + V3/ed?