The fire was finally brought under control,but not
__________heavy damage had been caused.
| A．before | B．after | C．since | D．as |
Professor Smith, along with his assistants, _________on the project day and night to meet the deadline.
| A．work | B．working | C．is working | D．are working |
There was so serious a matter that I had no choice but _________ the police.
| A．called in | B．calling on | C．call for | D．to call in |
The new research team was led by the ________engineer.
| A．main | B．major | C．chief | D．primary |
—Will you come?
—________you promise not to invite Mary.
| A．As if | B．If only | C．Only if | D．Even if |
They ________ to enter the building by the back door; however, the front door was locked.
| A．are supposed | B．aren’t supposed | C．weren’t supposed | D．were supposed |