1. My friend had studied English before he entered the institute
2.The car had gone when we looked into the street
3.He had taken the decision before I came
4. Nick had returned from office by seven o,clock
5.We got to the stadium at four o*clock but the game had already started
6. She came at six o'clock
7. I thought that my parents had already returned
8. He was sure that that we didn*t recognize him
9. You found your key which you had lost before / Did you find your key which you had lost before?
10. Meg said that she was in this city/Meg said that she had been in this city
11. The doctor arrived when we had already helped him
в некоторых предложениях возможны 2 варианта. проверь знак вопроса в пр. № 9!