limestone

这座古老的教堂是用当地开采的石灰岩建造的。

The ancient church was built with locally quarried ___limestone.

发电厂使用石灰石来减少废气中的硫含量。

The power plant uses ___limestone to reduce sulfur content in exhaust gases.

这种石灰岩地区常见溶洞和地下河。

Caves and underground rivers are common in this ___limestone region.