`1.`After they had cooked the meal, they had a party.

`2.`Before she wrote a report, she had discussed the lessons.

`3.`After he had died, she took up his position at the university.

`4.`Before the police arrived at the spot, the robbers had gotten away.

`=>`Form : Before `=`By the time `=`When + S + V2/ed, S + had + Vpp : Trước khi ai làm gì...

$\neq$ After + S + had Vpp, S + V2/ed : Sau khi ai làm gì...

`*`Hành động xảy ra trước chia ở quá khứ hoàn thành, hành động xảy ra sau chia ở thì quá khứ đơn.

`1.` After they had cooked the meal, they had a party.

`2.` Before she wrote a report, she had discussed the lessons.

`3.` After he had died, she took up his position at the university.

`4.` Before the police arrived at the spot, the robbers had gotten away. 

`@` After + S + had + V3/ed + O (TQKHT) , S + V2/ed + O (TQKĐ)

`->` Sau khi ai đó đã làm gì

`->` Diễn tả hành động xảy ra sau một hành động trong quá khứ. 

`@` Before + S + V2/ed + O (TQKĐ) , S + had + V3/ed + O (TQKHT)

`->` Trước khi ai đó đã làm gì

`->` Diễn tả hành động xảy ra trước một hành động trong quá khứ.