INVISIBLE ink has a lengthy history.

隐形墨水已经有一段历史了。

Think, think, think, think, invisible ink!

想，想，想，想，隐形墨水！

How do you tell when you run out of invisible ink?

要怎样才知道什么时候隐形墨水用完了？

the relevant part of the statement must be written in invisible ink.

声明中相关部分必须用隐形墨水书写。

"Appareo" is Latin for "appear" or "to become visible". Used to reveal invisible ink.

是拉丁文才“呈现”或者“现形”的意思，用来使得隐性墨水现形。