1.arrived..........had started 2.had lived...went
3.had eaten....began 4.had listened
5.hadn't arrived...left 6.had finished
7.was 8.had met
9.had forgotten 10.had study
11.hadn't rained 12.hadn't paid
==>thì quá khứ hoàn thành diễn tả hành động xảy ra trước 1 hành động khác trong quá khứ
==>when+S1+Ved/c2...,S2+had+Ved/c3
=>before+S1+Ved/c2...,S2+had+Ved/c3
=>after+s1+had+ved/c3...S2+Ved/c2
=>đk 3:if+S1+had+Ved/c3....,S2+would have Ved/c3