`1`. They (go) ..…went….... home after they (finish) ……had finished……… their work.
`2`. She said that she (already, see) ……had already seen……… Dr. Rice.
`3`. After taking a bath, he (go) ………went………… to bed.
`4`. He told me he (not/eat) ………hadn't eaten………… such kind of food before.
`5`. When he came to the stadium, the match (already/ begin) ……had already begun……
`6`. Before she (watch) ……watched…………….. TV, she (do) …had done…… homework.
`7`. What (do) …had he done…… he before he went to the airport?
`8`. After they (go) …had gone……, I(sit) ……sat……… down and (watch) …watched…… TV
`9`. Yesterday, John (go) ……had gone…… to the store before he (go) ……went…………… home.
`10`. She (win) ……won……… the gold medal in 1986.
`→` Công thức thì quá khứ đơn : S + V-ed
`→` Công thức thì quá khứ hoàn thành : S + had + $V_{( ed/ II)}$