Topologically , then , a sphere and a torus are distinct entities .

所以就拓扑学而言，球和环面是不同的东西。

We can classify swimsuits topologically by counting holes , say like this : assume the suit begins as a sphere , and we will cut holes so we can wear it .

用拓扑学我们可以通过数洞来给泳衣分类，像这样：我们假设泳衣一开始是个球体，我们为了能穿上它在上面剪一些洞。