The research is so designed that once ---（begin ）nothing can

1 你的句子在逻辑上有错误.begin的到底是The research还是nothing
所以,你的句子不能成立,站不住脚.it 到底指代什么?总之,（逻辑）主语不一致.是分词结构还是独立主格结构?
2 还有,在其他场合：begun是对的,beginning 也是对的,及物或者不及物已经不重要了.
3 关键是出题不严谨.
4 正确的句子是：
The research is so designed that once IT has begun // is begun （begin ）nothing can be done to change it --------
once IT has begun // is begun （begin ）nothing can be done to change it --------如果是状语从句结构,你的句子就对了.或者：
Once begun,it (==the research) will go on and nothing can be done to change it .
现在,你明白了吗?