The only thing .we could do was to ask the police for help.

The only thing .we could do was to ask the police for help.
A.what
B.who
C.that
D.whom
选C,为什么,另外,could能换成can吗?为什么能,为什么不能?
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-Could you tell me .for class yesterday?
-Because my bike was broke on the way.
A.why did you come late
B.why you came late
C.why do you come late
D.why you come late4
选B,为什么,其它的为什么不能选?
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希望得到好答案,请认真回答,
D选项的4是打多余的，不要看，那个选项是“why you come late"