to get to the bottom of
这种小事不必深究。
Such a small matter doesn't need to be investigated thoroughly.
深究原因何在
find out why through thorough investigation
汉译英翻译词典收录86165条汉英翻译词条，基本涵盖了全部常用中文字词的英语拼写、翻译、音标、读音、用法、例句等，是英语学习的有利工具。