Поставьте глаголы в скобках в соответствующую форму, Не did not know that the boss (to sign) the contract last week.

1. He did not know that the boss had signed the contract last week. 2. I am not sure, if I will leave Liberia next week. 3. Did he say that he had been writing a letter yesterday at five? 4. We decided that we would agree to their proposals. 5. I heard that you would telephone our partners in London next Monday. 6. We understood at once that the work was a difficult one. 7. When we came to the airport, the plane had already landed.