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    精英家教网 > 高中英语 > 题目详情
    The research is so designed that once ________ nothing can be done to change it.

    A．begins

    B．having begun

    C．beginnings

    D．begun

     

    答案：D
    解析：

    		对本题设空之前once一词用法的判断是做出正确选择的关键：

        once(或者其他连词如when，while，since等)引导状语从句时，如果从句主语与主句主语一致，可以省略其中的主语和be动词谓语结构，例如：

        Once in bed, the children usually stay there.

        (=Once they are in bed, the children usually stay there.)

        When finished, the building will be opened by the Prince of Wales.

        (=When it is finished, the building will be opened by the Prince of Wales.)

        While at college (=While she was at college), Delia wrote a novel.

        本题所给句子的句意为：

        The research is so designed that once it (=the research)is begun nothing can be done to change it．也就是：

        ...once begun nothing can be done to change it．

     


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