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.. Department of Homeland Security and CIA produced ______ joint report on Monday warning that ______ next 911 could in fact occur on ______ different date.
A.the; a; the B.a; the; a C./; the; the D.a; /; the
22. It is a strange phenomenon that some young people today think it is their parents’responsibility to earn money and_______ to spend it.
A.them B.they C.their D.theirs
23.Hearing that most of the members voted against her, she ______ a smiile.
A.wore B. managed C.performed D.controlled
24. The hunter calmly picked up his gun,took the aim an
