英语翻译Both of them research their family history as a hobby,but finding each other through traditional methods (such as sifting through census,marriage or property records) would have been unlikely if not impossible.——unlikely if not imposs

Question

英语翻译
Both of them research their family history as a hobby,but finding each other through traditional methods (such as sifting through census,marriage or property records) would have been unlikely if not impossible.——unlikely if not impossible是什么意思?我对多重否定经常容易看晕!

Answer 1

即使不是不可能的,也是靠不住的.
就是指,上面所说的“通过传统方式对家族史的研究”靠不住的.
碰到多重否定就把它掰开一个一个看,再连起来.