Pollution means adding dirty or harmful things to land, air, water and so on. As a result, they are no longer pleasant or safe to use. Pollution is bad for animals and plants, and it even makes people’s health in danger. In our daily life, we can see different kinds of pollution in many places. There are three main forms of pollution: land pollution, air pollution and water pollution. 
Land pollution is caused by solid waste, such as cans, bottles and some plastic things which aren’t broken down quickly. It makes the environment look very bad. However, air pollution is more serious than land pollution. It is much worse in cities and towns because of the fumes(废气) from traffic and the waste from human activities. When people drive their cars, fumes which are most made up of CO2, NO2 and SO2 are given off. After the gases get into the air, they may mix with clouds. Then they will become some harmful chemicals (化合物) falling on the ground with rain. It is one of the reasons for soil erosion (土壤侵蚀) which is one example of water pollution.
Various kinds of pollution will cause many health problems. People have realized they must change this serious situation. There are many ways to control pollution. To develop alternative energy is very popular in many countries. China, for example, has made up its mind to be a leader in this field. It is trying hard to make full use of energy from the sun and wind. It has paid plenty of money to make electric cars and trains instead of traditional traffic. We should also take action to make our environment cleaner every day. Take cloth bags while going shopping and drive cars less. We have only one earth. We must take steps now to help protect our environment for the future wherever we are.
How many main forms of pollution are mentioned in the passage?

A．Two.

B．Three.

C．Four.

D．Five.

Why is air pollution much worse in cities and towns?

A．Because of the cans and bottles that people throw away.

B．Because of the plastic things which aren’t broken down quickly.

C．Because of the fumes made up of SO2, CO2 and O2.

D．Because of the waste from human activities and the fumes from traffic.

Which of the following is TRUE according to the passage?

A．Pollution hardly does harm to humans.

B．China doesn’t want to develop alternative energy.

C．Air pollution will cause soil erosion and water pollution.

D．Land pollution is only caused by solid waste.

To make our environment cleaner, we shouldn’t __________.

A．use cloth bags while shopping	B．ride a bike to school
C．drive a car out every day	D．go to work on foot

The main idea of this passage is _________.

A．to introduce different forms of pollution and ways to control it

B．to introduce the harmful chemicals and the solid waste

C．to introduce the alternative energy and the ways to use it

D．to introduce the electric cars and traditional traffic