You’d better tidy up your room ________ your father comes back.
句意：你最好在你父亲回来之前清理你房间。
考查连词。so因此；or否则；before在……之前；but但是。“your father comes back”是时间状语，此处用before引导时间状语从句表示“在你父亲回来之前”。故选C。
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.
—Which book do you prefer, Harry Potter or Treasure Island?
—Harry Potter, of course, ____I ___ my sister likes it.
Millie’s research paper isn’t up to standard______ she has worked at it for two weeks.
