Making a mountain out of a molehill is an idiom referring to over-reactive, histrionic behaviour where a person makes too much of a minor issue. It seems to have come into existence in the 16th century.
英汉双解词典包含3185865条英汉词条，基本涵盖了全部常用单词的翻译及用法，是英语学习的有利工具。