The problem of air pollution is becoming more serious ______ the increasing number of cars.
I prefer a house in beautiful surroundings in the countryside to ________ in such a noisy street in Shanghai.
He is so young and short a man that I think he is ________ but a professor of Northwest University.
They have done much of the work; when will ________ be finished?
Mum, I need a new schoolbag. Could you buy ________ for me tomorrow?
The fact that she can't talk makes ________ difficult for her to communicate with her new classmates.