This is a question I got from a reader, an anonymous reader, and the subject line just said, "Urgent," and this was the entire email: "If people had wheels and could fly, how would we differentiate them from airplanes?"
这是我从一个读者那里得到的一个问题 一个匿名的读者 主题只是写了“紧急” 邮件内容如下： “如果人们有轮子而且能够飞 我们怎样把他们和飞机区分开来？”