hollow sphere

例句：

1. 1. The hollow sphere was a perfect fit for the hole in the wall.
   这个空心球完美地填补了墙上的洞。
2. 2. The hollow sphere was used as a weight for the balance.
   这个空心球被用作天平的砝码。
3. 3.The hollow sphere was filled with air to make it float.
   这个空心球被充满空气，使其能够漂浮。