问题
The commercial city, Loulan, used to be a stopping point on the silk road between the West and the East, ______ by sandstorms from AD200 to AD 400.
A:which is believed to be covered over
B:as is believed to have been covered over
C:it is believed to be covered over
D:which is believed to have been covered over;
B:as is believed to have been covered over
C:it is believed to be covered over
D:which is believed to have been covered over;
正确答案是：
同类题型
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They _______ the train until it disappeared (消失) in the distance (在远处).
The police tried _____ to break up the protest crowds[ ]
Lily, _______ apple on the table is for you.—Thanks, Mum. _______ apple a day is good for us.