题目内容
7.Loulan is believedto have been covered (cover) over gradually by sandstorms from AD200to AD400.分析 据信,楼兰是从公元200年到公元400年之间逐渐被沙尘暴覆盖的.
解答 答案是to have been covered.本题考查动词不定式的用法;"据说/信/认为/报导…"常常用句型"It be said/believed/reported…that",该句型可以转换成"sb./sth.be said/believed/reported to do/to be doing/to have done";楼兰已经被沙尘暴覆盖,故用动词不定式的完成式的被动语态,所以答案是to have been covered.
点评 本题是要求用所给动词的适当形式填空,解题时首先考虑句中需要的是谓语动词还是非谓语动词;其次,如果是谓语动词关注时态、语态和数的变化;如果是非谓语动词要联系非谓语的基本用法判断非谓语的形式.
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