It is widely believed that Chengdu Subway is to play an important part in our lives once it ________ by 2010．A.will be pletedB.has been pletedC.can be pletedD.is going to be pleted
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B解析考查动词时态。在时间状语从句、条件状语从句和让步状语从句中常用一般现在时代替将来时。本题是由once引导的条件状语从句，故A和D不正确；同时根据题干中的by 2010可知强调完成，因此