She laid a spring mattress under the sheet.

她在床单下面铺了一个弹簧床垫。

youdao

Think of each sheet as a separate spring.

你可以把每一张汽泡纸看作一个弹簧。

youdao

Maybe you can see that what I really need is Young's modulus for bubble wrap and not the spring constant of an individual sheet.

现在你大概能够看出我真正需要的其实是汽泡纸的杨氏模量而非一张纸的弹性系数。

youdao