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  • 更新 2022-09-03
  • 科目 英语
  • 题型 单选题
  • 难度 中等
  • 浏览 1293

While every possible means __________ to prevent the river pollution, the river in my hometown has still not been restored to its past beauty.

A.is tried B.are tried
C.has been tried D.have been tried
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Whileeverypossiblemeanstopreve