Put near large cities,natural vegetation becomes scarce,and introduced trees,ornamental shrubs and gardens are far from adequate in absorbing motor vehicle and industrial air pollutants.

• 可是邻近大城市地区的天然植被日渐稀少，而移植树木、观赏灌木及花园，又远不足以吸收机动车辆和工业带来的空气污染物质。