How do you know their

"That's an awfully exact number, " says the tourist. "How do you know their age so precisely?"

“真是个不可思议的数字”游客说“你怎么知道得这么准确”。

So we recognize the fact that, you know, people can pretty much figure out how to do their own work.

所以我们认识到真正的事实是，您知道，人们能够非常明确地指出如何完成他们自己的工作。

How do you know anyone is who he/she says he is, especially when they put up pictures of themselves that might be their feet, or a cat, or a Mardi Gras mask, or a tin of Spam?

你怎么能通过别人说他/她谁就知道他/她呢？ 特别是他们用他们的脚、一只猫、一个狂欢节面具或肉罐头作为他们的头像的时候。