—Is the letter from your mother?—Yes.But she ________the letter herself,because she doesn’t even know one word.
It_____we had stayed together for several weeks_____ I found we had a lot in common.
You_____ all those calculations! We have a computer to do that sort of thing.
—_____I stay with you?— Well, I would rather you_____me alone for a while.
Mr. Black is a careful and experienfed engineer, so he is often _____ to finish some challenging tasks.
China is a peace-loving country and _____no circumstances _____ first use nuclear weapons.