It's balancing on a shaft and a ball, right at the center of gravity, or just slightly above the center of gravity, which means that the lower half of the object is just a little bit more weighty.
这在一根箭杆和一个圆球上保持着平衡， 就在重心处，或者说，重心上方一点点， 这意味着 物体下半部比上半部重一点点。