题目内容
The research is so designed that once _______ nothing can be done to change it.
A. begins B. having begun
C. beginning D. begun
D
解析:
D。由于 the research 与 begin 是被动关系,故用过去分词 begun。Once begun 可视为 once it is begun 之省略。
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题目内容
The research is so designed that once _______ nothing can be done to change it.
A. begins B. having begun
C. beginning D. begun
D
D。由于 the research 与 begin 是被动关系,故用过去分词 begun。Once begun 可视为 once it is begun 之省略。
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