平邮 用英语怎么说？

surface mail

「平邮」的英文是 surface mail，走海运或陆运的普通慢速邮件，比 airmail 便宜但慢。

If you want to save money, you can send the books by surface mail; they will take about six weeks to arrive.

如果想省钱，你可以用平邮寄这些书，大约六周才能到。

The parcel was shipped by surface mail, so it has no tracking number and cannot be delivered any faster.

这个包裹走的是平邮，所以没有追踪单号，也没法更快派送。