Вставьте нужные формы:
1. We........over the phone while he....... his hometask.
a. talked, doing b. were talking, was doing c. was talking , were doing
2. Oh, I m sorry, I haven’t ......you at first.
a. understanding b. understood c. understand
3. He was so tired that he couldn’ t......us.
a. to join b. joined c. join
4. We shall..... .the result when we finish our experiments,
a. to be discussing b. to discuss c. discuss
5. We... to the theater this month.
a. are not b. have not been c. were not