know something like the back of your hand idiom informal
精通;对…了如指掌
to have very good and detailed knowledge of something
I know this area like the back of my hand. 我对这一地区了如指掌。
江苏热线英汉汉英双解词典包含207361条英汉翻译词条，涵盖了常用英语单词及词组短语的翻译及用法，是英语学习的必备工具。