Theresearchtheyhadbeendevotedto__

发布时间：2020-07-12 07:37:44

The research they had been devoted to ______ to be of great value to the cancer patients












A.is proved











B.proves










C.has proved










D.proved

网友回答

D解析考查时态。句意：他们一直从事的研究证明对治疗癌症病人有巨大价值。they had been devoted to为后置定语从句。结合语境可知本句描述的是过去发生的动作，故用过去时态。选D。
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