车库的地面是用混凝土铺成的。

The floor of the garage is made of ___concrete.

钢筋混凝土常用于桥梁建设。

Reinforced ___concrete is commonly used in bridge construction.

现代城市常以灰色混凝土建造的高楼为特色。

Modern cities often feature tall buildings built with gray ___concrete.