Frankly speaking, ________ of them knew what the other was doing that morning.

Forty percent of the students in our class are boys, ____are girls.

The chairman thought________necessary to invite Professor Smith to speak at the meeting .

—What can I do for you?—I’d like to buy a computer for my son, ______ at a good price but of great quality．

The case of Li Gang became a hot topic and so did ______of Li Tianyi.