1.When we (arrive)arrived, the show (begin) had already begun.
2.I (come)came to see her but she (not be)wasn't at home. Her mother (say)said she (go)had gone out with her friends.
3.I (not hear) hadn't heard from him for years before I (meet)met him again yesterday.
4.When I (do)did my homework, I (watch)had watched a game show on TV.
5.Daddy (get)got angry because Tim (lose)had lost his passport.
6.- When did you leave the office? – When I (type)had typed the report.
7.It was the best film I had ever (see)seen. 
8.By the time he (leave)left, he (turn) had turned off all the lights.

==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

=>it/this+was+the best+noun+S+had+(ever)+Ved/c3

1. arrived - had begun

-> When QKĐ, QKHT

2. came - wasn't - said - had gone

-> thì QKHT: S had VPII

3. hadn't heard - met

-> QKHT before QKĐ

4. had done - watched

-> thì QKHT: S had VPII

5. got - had lost

-> thì QKHT: S had VPII

6. had typed

-> thì QKHT: S had VPII

7. had ever seen

-> thì QKHT: S had VPII

8. left - had turned

-> By the time QKĐ, QKHT