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. ------Mum，can I go out to play with Tom for just a while ？
------ _______ and do what you like.
A. No way B. Go ahead C. It depends D. Don’t worry
22. The driver was at ___ loss when _____ word came that he was forbidden to drive for speeding.
A. a; the B. /; / C. the; the D. a; /
23. ------ Bob failed in the exam again .
------ He _____ it ; he never worked hard .
A. deserved B. succeeded C. missed D. considered
24. ---- How long will it be ______ we know the result of the English examination?
----- Perhaps in two or three days.
A. since B. before C. until D. that
