---Haveyoufinishedtheplan?---Yes,andit_________bytheexpertsforthreetim

发布时间：2020-08-07 04:24:36

---Have you finished the plan?---Yes, and it _________ by the experts for three times．A.was being studiedB.has studiedC.has been studiedD.studied

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C解析for three times应与完成时连用，且表“被研究”，为被动语态。
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