noun · a broad, flat, and usually rectangular piece of stone used for paving, walkways, or construction

老城的街道是用厚重的青石板铺成的。

noun · a fine-grained metamorphic rock that splits into thin layers, or a piece of this rock used as a roofing tile or writing surface

这种石板质地坚硬，常被用来制作房顶的瓦片。