spheres
A sphere is an object that is completely round in shape like a ball.
Because the earth spins, it is not a perfect sphere.
因为地球旋转,所以它不是个完完全全的球体。
the volume of a hollow sphere.
空心球的容积。
A sphere of activity or interest is a particular area of activity or interest.
the sphere of international politics.
国际政治领域。
nurses, working in all spheres of the health service.
在医疗卫生各个领域工作的护士。