请大家帮忙分析一下这个句子！

But that prediction would not have adversely affected the dollar had it not been for the government’s huge budget deficit, which must therefore be decreased to prevent future currency declines.

这是og逻辑中的句子，但在下遇到的是对该句的语法不懂的问题！还请帮忙分析一下

！

But that prediction would not have adversely affected the dollar

if  it had not been for the government’s huge budget deficit, which must therefore be decreased to prevent future currency declines.

IF虚拟语气的省略方式。省去IF，把从句部分倒装。SHOULD，WERE也有此类似用法。刘振民语法有此语法说明。

美美所言既是，我原本也是这样想可终究书读得少不敢肯定，谢谢