Loulan is believed __________ over by sandstorms gradually from AD200 to AD400.A.to cover B.to be coveredC.to have coveredD.to have been covered
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D解析试题分析：考查句型：sb/sth is believed to do/to have done,据相信某人/某物…，如果是将要做，用不定式一般式to do如果是已经做了，用不定式的完成式，句意：大家相信楼兰是从公元前200年到公元前400年逐渐被沙尘暴淹没的。因为楼兰是被掩埋的，用不定式完成式的被动，选D。考点：考查固定句型点评：固定句型是学习语言的重要环节。sb/sth is reported /believed to do/to have done,可以转化成It is reported /believed that句型，解答这类题目，关键是理解题干意思从而判断是动词不定式的什么形式，根据意思放入句子中进行比较，不难选出正确