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.It is announced that $20,000 reward will be offered for return of the stolen sculpture.
A.a;the B./，the C.a;a D./; a
22．--Shall I give you a ride to the Capital Airport?
--Thank you．________．
A．If you like B．It couldn’t be better
C．Of course, you can D．It’s up to you
23.—Jane, have you finished your’paper?
—No,I my sister with her homework all the morning.
A.help B. helped C. have been helping D.was helpin
