hard center noz

例句：

1. 1. The hard center of the earthis where the tectonic plates meet.
   地球的硬心是地壳板块相遇的地方。
2. 2. The scientist found that the hard centerof the planet was not as stable asthey had thought.
   科学家发现星球的硬心并不像他们所认为的那样稳定。
3. 3. The hardcenter of the city is the business district, which is bustling with activity.
   城市的硬心是商业区，那里充满了活动。