Question

4. Before yesterday, I ... that man in our office. 5. I used my time well while I ... for my plane - I wrote some emails. 6. By the time he returned, I ... my work on the report.
4.а)didn't see b)was not seeing c)had not seen
5.a)waited b)was waiting c)has waited
6.a)finished b)was finishing c)has finished ​

Answer 1

Ответ:

4) c) had not seen

5) b) was waiting

6) c) has finished ​

(хотя в №6, по моему, должен быть Past Perfect - had finished)