Of course, social science research is almost never conclusive. There are always methodological difficulties and stones left unturned.当然，社会科学的研究几乎从来没有结论。总是有方法上的困难和人事未能尽到的情形。
The police left no stone unturned in their search for the missing child.警察为了寻找这个失踪的儿童，使用了一要手段。
