Examples: a)My parents had already eaten by the time I got there. b)Until yesterday, I had never heard about it. c)The thief simply walked in.someone had forgotten to lock the door. _The past perfect is a 'before past' tense, it is used to indicate an action that was completed before another action happened _We form the past perfect with 'had+the past participle(gone/opened/written...) d)Sam had already left when we got there. e)Sam had left before we got there. Sam left before we got there. f)After the guests had left, I went to bed. After the guests left ,I went to bed. _If either 'before' or 'after' is used in the sentence, the past perfect is often not necessary because the time relationship is already clear.The simple past may be used, as in (e) and (f) Exercise: Use the simple past or the past perfect. 1-He(be)a journalist before he(become)a businessman. 2-I (feel) a little better after I (take) the medicine. 3-I was late.the teacher (already/give) a quiz when I (get) to class. 4-when I (get) home, I found that someone (break)into my house and (steal) my fur coat. 5-John (go) into the army as soon as he (finish) his studies. 6-I(never/see) any Picasso's paintings before I (visit) the art museum. 7-Once he (eat) the food, he (pick) his bag and(leave). 8-Tom (not/be) at home when I (arrive).He(just/go)out 9-When I (go) to my home town after many years, I(not/recognize) Mrs Johnson.She(change) a lot . 10-The house(be)very quit when I(get)home.Everybody (go) to bed. GooD Luck ! Yasmiina