Christina wasn’t saying anything, but the professor smiled at her _______she had done something very clever

The number of people in the party _____fifty, but a number of them ____ absent for different reasons.

The first prize winner_______, John was so disappointed that he felt unwilling to know the rest results[ ]

What do you think is the best way to the pollution problem

The two girls had been talking in ________ low voice all ________ time during the meeting, which upset the manager.