yán / jiū / rén / yuán / zhuī / gēn / sù / yuán / zhōng / yú / zhǎo / dào / le / wèn / tí / de / zhēn / zhèng / yuán / yīn

研究人员追根溯源，终于找到了问题的真正原因。

The researchers traced the problem back to its source and finally found the real cause.