The research is so designed that once nothing can be done to change it . A.begins B.having beg——青夏教育精英家教网—

摘要：The research is so designed that once nothing can be done to change it . A.begins B.having begun C.beginning D.begun ada and Australia help to English food. A.provide - for B.supplu - to C.provide - with D.supply- with

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(NMET 2002)The research is so designed that once ________ nothing can be done to change it.