Hundreds of people __in thr building when the terrible fire broke out.

题目

Hundreds of people __in thr building when the terrible fire broke out.
A.reported to be trapped B.were reported to trap C.were reported trapped 为什么选C.

答案

据报道,大火发生的时候有几百人被困在大楼中.
be reported (to be) trapped原句是这个,to be被省略了.