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精英家教網(wǎng) > 高中英語 > 題目詳情

The research is so designed that once _______ nothing can be done to change it.

A. begins B. having begun

C. beginning D. begun

解析:

D。由于 the research 與 begin 是被動關系，故用過去分詞 begun。Once begun 可視為 once it is begun 之省略。

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科目：高中英語 來源： 題型：053

閱讀理解：　　

閱讀下面短文，從所給四個選項中，選出最佳答案。

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