Whenshesings,Carol’svoicemustbelo

发布时间：2020-07-26 14:17:33

When she sings, Carol’s voice must be loud enough ________ by four thousand people．A.to hearB.to be heardC.having heardD.being heard

网友回答

B解析enough修饰loud，后面接动词不定式，hear与voice是被动关系，所以要用不定式被动形式。
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