Today more and more people live in cities. So there is usually little room in a city to grow food.1of the land in a city is used 2 homes, shops, roads and parks. Most food for city people is grown in the country. It is often brought to the city by3, train and plane. Some food 4 comes into the city by car.
Water is5 thing that cities get from the country. Everyone needs water every day. We use a little of it for6, but we use even more to 7bathtubs(浴缸) and wash streets.
The water used in cities comes mostly from the rain. But people8use the rain that falls on cities. The rain becomes dirty as it falls through dirty air. Once it hits city buildings or streets, the rain will pick up more dirt. It is not good for drinking or bathing.
So cities must reach out to the 9 country for water. There the rain falls through air onto trees and grass. The fallen rain runs 10 rivers and lakes. So it is important to keep both cities and the country clean.
