Kahn also paid careful attention to the use of sunlight.

VOA: special.2009.12.13

And again, you've got to be careful about how you use the operators.

再提醒一次，你们用运算符的时候,要多加小心。

麻省理工公开课 - 计算机科学及编程导论课程节选

Of course, you've got to be a little careful when you use it.

当然,使用公式时也要小心点儿

耶鲁公开课 - 基础物理课程节选