inner ring

例句：

1. 1. The inner ring of the planet is made up of liquid metals.
   行星的内圈由液态金属组成。
2. 2.The inner ring of the city's transportation system is efficient and fast.
   城市的交通系统内圈是高效且快速的。
3. 3.The inner ring of the forest was dense with life.
   森林的内圈充满了生命。