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
He _________his friend in the crowd at the first sight and called out his name.
A. spotted B. watched C. observed D. glared
