At the time of the earthquake Jeff was still in his office. He ________ to finish a project before he left for the day.A.has triedB.had triedC.has been tryingD.had been trying
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D解析指从发生地震之前的某一时候开始到发生地震时一直在努力完成一项计划，并且在发生地震时依然在办公室努力完成这一计划，所以要用过去完成进行时。