No one knows when such a custom first came into existence. 沒有人知道這種風俗什麼時候開始有的。
Do you know when this kind of robot came into existence? 你知道這種機器人是什麼時候問世的嗎？
The Government had intended to limit the wage increases of all workers to a reasonable amount, but several trade unions got a march on them by receiving very large increases before the new laws came into existence. 政府部門本來打算把所有工人的加薪幅度限制在一個合理的水平上，但是幾個行業工會搶先一步，在新的法規出台之前就獲得了大幅度的加薪。
