公共医疗系统是社会的重要平衡器，确保每个人都能获得医疗服务。

The public healthcare system is an important ___leveller, ensuring everyone has access to medical services.

在铺新地板之前，我们需要用水平仪确保地面完全平整。

Before laying the new floor, we need to use a ___leveller to make sure the ground is perfectly flat.