why ... not
⇒ 何不叫你女朋友一起来？
Why don't you ask your girlfriend to come too?
⇒ 既然有事,何不早说？
You may have had things to do, but why didn't you say so earlier?
英语词典包含298861条英英释义在线翻译词条，基本涵盖了全部常用单词的英英翻译及用法，是英语学习的有利工具。