从 A、B、C、D 四个选项中，选出可以填入空白处的最佳选项，并在答题卡上将该项涂黑。
21. —____________, sir?
—The Prince Hotel, on the 15th Avenue.
A. What's on B. What's up C. How far D. Where to
22. Some day in the future, __________will be possible for us to walk _____________.
A. this; in space B. it; in space C. this; in the space D. it; in the space
