英语句式解析:"had it not been for the diamonds"前面是否需要连词?it指代什么?

问题描述:

英语句式解析:"had it not been for the diamonds"前面是否需要连词?it指代什么?
原句:The reasearch has been underway in southern Africa for four years now,and it problably wouldn't have happened there had it not been for the diamonds.

不用连词,这半句原本用if连接的从句,但是改为了倒装句式,连词就省略掉了.it指的是前半句说的那个research.