know what's what idiom informal
懂行;老练
If you know what's what, you have a lot of experience and can judge people and situations well.
Linda's been in the business for 30 years - she knows what's what. 琳达从事这一行已有30年了——她很懂行。
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。