3．
根据材料内容，选择正确答案。 Shenzhen's fast development has made it become China's most crowded city! Here are about 15 million people living on its 1,991 square kilometers. On each square kilometer averagely(平均地) live 7, 500 people. It is 1, 080 more than that in Hong Kong, and nearly 800 more than that in Guangzhou.
Besides, Shenzhen owns 2 million local vehicles, and about 300, 000 vehicles from other places also run on the local roads every day. The total length of the city's roads is 6, 041 kilometers. It means each resident only owns 0. 58 meters of road!
As a result, the city is facing serious environment and resource(能源) problem. One of the problems is water shortage. The amount of fresh water for each person of the city is only 25％ of the country's average. What's more, most of the water drunk by Shenzhen people comes from other areas.
