买水管、延长线或梯子时,买比你认为需要的长得多的。才会是正确的尺寸。
When buying a garden hose, an extension cord, or a ladder, get one substantially longer than you think you need. It’ll be the right size.
地球形状的问题本质上是引力和旋转共同作用下的平衡问题。