从A、B、C、D四个选项中，选出最佳选项，并在答题纸上将该项标号涂黑。
21. I was told that 10:15 flight would take us to Shanghai in time to reach Fudan University．
A．the; / B．the; a C．a; the D．/; the
22. I wish I could offer you some cake but there’s _______ left.
A. nothing B. none C. nobody D. no one
23. I thought we’d be late for the concert, _______ we ended up getting there ahead of time.
A. but B. or C. so D. for
