Take a look at your day. The roof of your home is probably made waterproof by an oil product, bitumen. The same product is used for the road surface outside your home.

• 请看一看你的日常生活。你家的屋顶可能是用一种叫沥青的石油产品做成防水的。沥青同样可用来铺你家外面的路面。