拱心石

例句：

1. 1. The bridge is supported by a large stone arch at the center, which is known asthe "Arc of the Heart."
   这座桥的中心有一个大石头拱门，被称为“心形拱”。
2. 2. The ancient city walls were built with solid stone blocks, providing a strong defensive structure for the city.
   古老的城墙是用坚固的石块建造的，为城市提供了强大的防御结构。
3. 3.The construction of this bridge required the placement of several large stones to form the arch.
   这座桥的建设需要放置几块大石头来形成拱门。