The city is believed over by sandstorms from AD200 to AD400.
A. to cover
B. to be covered
C. to have been covered
D. that was covered
网友回答
A. to cover
B. to be covered
(答案→)C. to have been covered
D. that was covered
解析：The city与cover之间是被动关系，故用不定时的被动式；cover这个动作发生在believe之前，故用不定式的被动式的完成时，故选C。