信心满满的做英语题目,没想到第一题就把我难住了!The research is so designed that once ____英语解答

信心满满的做英语题目,没想到第一题就把我难住了!
The research is so designed that once _____ nothing can be done to change it.
A.begins
B.having begun
C.beginning
D.begun

人气：254 ℃　时间：2020-09-19 06:48:51

解答

选 D begun
一旦开始,没有东西可以改变它.
once begun=once it is begun 算被动语态
这里有虚拟的意思,因为没有开始,所以用begun