英语翻译

题目

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!

答案

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.