—Michael, shall we go hiking in the mountains next Sunday?
—OK, ________it rains heavily.
句意：——迈克尔，下星期天我们去山上远足好吗？——好的，除非下大雨。
考查连词辨析。when当……时；until直到；unless除非；if如果。下文“it rains heavily”表否定的条件，故应用unless连接，即除非下大雨，否则我们就去远足。故选C。
—Michael, shall we go hiking in the mountains next Sunday?
—OK, ________it rains heavily.
The young men all shouted “Happy New Year” _______it was twelve o’clock.
You’d better tidy up your room ________ your father comes back.
A break between classes is very important for students because it ________helps with students' health by doing sports _______improves their social skills by communicating with their classmates.
You'd better make a good plan you take a holiday.
Cooking is an interesting lesson and we can make different dishes ________ we like.
—Would you like to play table tennis with me this afternoon?
—I'd like to. ________ I'm afraid I have no time.
Susan ________Tina are good friends.
Miss Zhao is very helpful. She often helps us ____we are in trouble.
He was so tired that he fell asleep ___he went to bed.
