-----How long do you think it will be _____man can finally solve the problem of cancer?------Well.it depends.
He began to ______because every means ______ tried already.
It’s said that the old lady died______.
______ water to grow is well known.
China has made a promise________ she will try her best to keep the world peace.
Mary, it's already 7 0'clock I'm afraid there is not much time ________for you to ________ for the ball.