问题
选择题
The research is so designed that once _______ nothing can be done to change it.
A.begins
B.having begun
C.beginning
D.begun
答案
答案:D
“连词+分词”作状语,依然由句子主语与分词的关系来确定,主动关系用现在分词,被动关系用过去分词。the research 与 begin 是被动关系,用过去分词 begun。