第一节 单项填空（共15小题，每小题1分，满分15分）
从A、B、C、D四个选项中，选出可以填入空白处的最佳选项。
21. You are a manager. It's ______ you to decide what to do next.
A. up of B. up for C. up to D. up on
22. His parents suggested that we ____ at home preparing the lessons, but he disagreed.
A .stay B. staying C. stays D. stayed
23. — What about going to the cinema this evening?
— Oh, I don’t know．I’ve got a bit of a headache． ____, John’s coming to see me, so I ought to stay in．
A．However B．In other words C．What’s more D．Though
