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    So far, every possible means to protect the river from being polluted, but pollution is still very serious. A. has used B. have used C. has been used D. have been used 【查看更多】

     

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    So far, every possible means ___ to protect the river from being polluted, but pollution

    is still very serious.

    A. has used　　　　 B. have used 　　 C. has been used　　 D. have been used

     

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