A ball, on the other hand, can be turned into a doughnut only by either boring a hole through its middle or stretching it into a cylinder and gluing the ends together.

• 反之，如果想把一个球变形成甜甜圈，你就得在球的中心穿个洞，或是将它拉成圆柱形然后把两端黏在一起。