We have only one earth
Today the earth is destroyed so terribly from the air to the land.In most of cities in all over the world,people always have to live in the polluted air.Heavy traffic and factories cause this.The gas,which is made by the cars and factories,is poisonous.They cause air pollution in the city.As a result,in 1952,thick dark pieces of cloud came down over London.People called it " a pea-soupier ".The smog was rather dangerous,especially to the old people and the young children.Thousands of them died.So in 1956 the British government decided to amend the law to keep the air clean.It stopped people from burning dirty coal in house and factories in the city.We can not live without air.So we must do everything possible to keep it clear and clean.
The area of desert is growing every year.This is a serious problem all over the world.About 350 years ago,nearly half of the USA was covered with forest.But now there is no one third left.The forest has almost gone and a lot of good land has gone with it.The reason for this is that too many trees are cut down.So when it rains,the soil is washed away,leaving only sand,but no trees and no any good land.No land means we will have no food.Then how can we go on living in the future?So we must try our best to plant more and more trees in order to protect the land.
We have only one earth .If we do not take good care of it,we will have no places to live on.
