I wil say nothing about this unless I am sure of the factsunless 为什么不用if 好像也说得通啊

I wil say nothing about this unless I am sure of the factsunless 为什么不用if 好像也说得通啊
I wil say nothing about this unless I am sure of the facts
unless
为什么不用if 好像也说得通啊

I wil say nothing about this unless I am sure of the factsunless 为什么不用if 好像也说得通啊
I will say nothing about this unless I am sure of the facts.
译：除非我对这些事实已经非常肯定了,我不会说任何有关这件事的情况的.
不能只用if.但如果把unless换成if...not,那是可以的.
I will say nothing about this (if) I am (not) sure of the facts.