reminder

He left a sticky note on the fridge as a reminder to buy milk on his way home.

(Chinese) 他在冰箱上贴了一张便签，提醒自己回家路上买牛奶。

The scar on his arm served as a permanent reminder of the bicycle accident he had as a child.

(Chinese) 手臂上的伤疤成了他儿时自行车事故的永久提醒。