In order to keep the balance of ecosystem, every possible means to deal with the problems

In order to keep the balance of ecosystem, every possible means to deal with the problems of the over-exploiting of natural resources.
A. has tried
B. has been tried
C. have taken
D. have been taken

A. has tried (答案→)B. has been triedC. have takenD. have been taken解析：考查主谓一致和语态。Means（方式，方法）是一个单复数同形的名词。本题means前面有every修饰，说明本句中的means是一个单数形式，故谓语部分使用单数形式，排除CD。句意：为了保持生态的平衡，每一种可能的方式都已经被使用了来处理过度使用自然资源的问题。故使用被动语态。B项正确。

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