---Do you need any help with the box? ---No, thank you. I can _____ to make it.
I want to be a doctor when I _______.
— Which sport will you take part in? — The ______ race.
—Humans can’t live _______ air. —I agree with you.
He____know the answer, but I’m not sure. A. maybe B. may be C:may D. must
—_______ can I keep the books? —Two weeks.