Polishing Gravels: Before floor tiles became the main building material, the floor was covered with gravels and cement and then polished. 磨石子工藝：在地磚成為主要建材前的室內地板工藝, 將地上鋪滿碎石與水泥後拋光。 These images are for RF download on Pixta Stock. Just click each image for the resource, thanks. Stocks on Image Coffee Lite: Click Here.