选择题39）An ambulance and some police cars were waiting in fron

选择题39）An ambulance and some police cars were waiting in front of the house,with doctors running
An ambulance and some police cars were waiting in front of the house,with doctors running in and out and some polimen standing nearby.Somebody ________ injured or killed.
A.must have been
B.should have been
C.must been
D.would have been
C是must be