Сделайте пажалуйста английский,даю 20 баллов​

Ответ:

1 The scientist had been working at the experiment for a year when it was solved.

2 We had been packing our things for two hours when it was time to go to the railway station.

3 The young man had been working at the laboratory for two years when he decided to enter the university.

4 The members of the expeditions had been making the preparations for some months when they started for the North.