把If it weren't for their support,we would be in a diffcult situation.的条件句的weren't提前.

在书面语或一些口语中,条件从句可以不用连接词if,而把谓语里的过去式were、had、should移到主语之前,构成部分倒装,但这种部分倒装里的助动词是不能用缩写形式的,如：
Were you in my position,you would do the same.
Had he been in your position,he'd probably have done the same.
Should they attack us,we'll wipe them out completely.
I will go,should it be necessary.
在虚拟时态中,可移到主语之前的,除了were、had、should外,偶尔还有did、would、could等助动词和情态动词.如：
There are other articles,to which,did time permit,we might draw attention.
Would space allow,I would like to quote the notice in full.
"Joyce!" and Joyce would have been astonished could she have heard his voice.
Did I have time,I would come.
你给出的句子,正确的说法是Were it not for their support,we would be in a difficult situation.意思是：“没有了他们的支持,我们就处于很困难的境地了.”这里的were与否定字not不可以缩写.希望我能帮助你解疑释惑.