send:vt. 发送，寄；派遣；使进入；发射vi. 派人；寄信n. 上升运动I sent to invite her to hang out with me.我发信息邀请她和我一起出去逛街。

John was sent to Africa for training.约翰被派遣到非洲进行培训。I'll send her a letter next week.下周我会给她寄一封信。post:n. 岗位；邮件；标杆vt. 张贴；公布；邮递；布置vi. 快速行进Did you remember to post my letter 你记得帮我寄信了吗？My letter must have got lost in the post.我的信肯定在邮递中丢失了？mail:n. 邮件；邮政，邮递；盔甲vt. 邮寄；给…穿盔甲vi. 邮寄；寄出The mail was delivered to her house.信件送到了她家。

send是动词，意思是发送，寄出

post也是动词，意思是发布

mail也是动词，意思是寄信，寄包裹