common purite

例句：

1. 1. The common purity of the water is not high enough for drinking.
   水的普通纯度不够高，不适合饮用。
2. 2. The common purity of the air in this area is relatively low.
   这个地区的空气普遍纯度较低。
3. 3. The common purity of the soil in this region is very good, which is beneficial to plant growth.
   该地区土壤的普遍纯度非常好，对植物生长非常有利。