释义：
be sure to 一定……
在嘱咐对方一定做某事时所使用到的句式。可以用祈使句的形态 Be sure to ,也可以说成 I'll be sure to ...。
例句：
Be sure to check them all.
一定要检查一遍。
You'll be sure to send me flowers first.
你一定要先送我花。
I'll be sure to double-check everything from now on.
从现在开始，我一定要检查两遍。
对话：
A: I'm going to stay up late tonight.
我今晩打算熬夜。
B: Be sure to brush your teeth before going to bed.
你睡觉前一定要刷牙。