—When ____your sister the computer? —Last month. A. does, buys B. did, buy C. did, buys
一Excuse me, where can I exchange _______? 一There is a bank on the second floor.
Basketball is so popular a game in the world that ______ people play it for fun and exercise.
Don't be afraid of asking for help ______it is needed.
I want to know______do to improve my English.
It's important______the piano well.