a written permission, he had to write another letter to the president of the university.
Professor Smith, along with his assistants, _________on the project day and night to meet the deadline.
There was so serious a matter that I had no choice but _________ the police.
The new research team was led by the ________engineer.
—Will you come?—________you promise not to invite Mary.
They ________ to enter the building by the back door; however, the front door was locked.