—Is Tom in the next room?—Well,it’s hard to say.But I heard him________loudly when I passed by just now.
Bob doesn’t know _____ to write about.
We must be strict _____ ourselves and strict _____ our work.
Now more and more people prefer__to__in order to reduce the air pollution.
They would rather___colours like orange or yellow than blue or white.
Do you like ____ books ?