The research is so designed that once _____ nothing can be done to change it.A.beginsB.having begun

题目简介

The research is so designed that once _____ nothing can be done to change it.A.beginsB.having begun

题目详情

The research is so designed that once _____ nothing can be done to change it.
A.beginsB.having begunC.beginningD.begun
题型:单选题难度:偏易来源:不详

答案

D
可视为once it is begun之省略。

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