Newton is not going to come and tell you what force the spring will exert when it's pulled by some amount.

牛顿不会过来告诉你,弹簧被拉伸一定量时会产生多大的力

耶鲁公开课 - 基础物理课程节选

Let's say they're telling you, you have to do something, you have to do something.

假设他们告诉你，你必须去做某事，一定得做某事。

The thing is 课堂 - SpeakingMax英语口语达人