When I entered the room, I found a little boy _____ on his mother’s knees _____ to draw a picture.
She could not speak, nor ______anything we said.
Why many adolescents (青少年) have trouble communicating with their parents lies in _____we call “generation gap.”
You’ve been working all morning — I think you _____a rest.
We drew this conclusion on the _______of research and experiments.
They are all interested in the newly-built apartments along the river, really want to buy them yet.