—What's the matter with the man hanging his head there?—Well,if you ________ know, he was caught stealing my bike.
My little sister had an apple in __ his hands.
Reagan was elected ___ of the United States in 1981.
This is the best film __ we have seen this year.
He has a poor memory.He has forgotten ___ his dictionary while reading.
They devote themselves to __ a new way to make populated water clean.