reason
知其然而不知其所以然
know what it is but not why it is so
他说了半天，还是没说出个所以然来。
He talked on for ages but did not say anything useful.
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。