--Look!Whyaretheresomanypeople?--Therearesomepolicemen....

问题详情：

--Look! Why are there so many people?

--There are some policemen. I think there ________ a traffic accident.

A. must have    B. can have            C. is going to be              D. must be

【回答】

D 

知识点：情态动词

题型：选择题