Ответ:

1) You had not left the hotel by our arrival yesterday.

2) How many letters had she typed by the end of the day?

3) Had he have dinner by that time?

4) My cousin had not been to this museum before.

5) I had got your message two days before.

6) What had he done by the end of last week?

7) What places had they visited by the end of their vacations?

8) Whom had he phoned before his departure?

9) She had bought a new fridge by the end of last week.

10) Ben had taken the medicine by five o'clock yesterday.