Since the first Earth Day started on April 22, 1970, people around the world have been encouraged to protect the environment and natural resources．Gaylord Nelson started this holiday．On the first Earth Day， 20 million people took part in Earth Day events．
Earth Day activities can include learning something about technology like cars that are more environmentally friendly and special houses that save energy and water．An organization called the Earth Day Network encourages people to use clean energy which doesn’t pollute the environment．Most of our energy comes from fossil fuels (化石燃料) that are found underground． Coal， oil and natural gas are examples of fossil fuels．Fossil fuels come from plants and animals that lived millions of years ago． Burning fossil fuels to create energy pollutes the air and water． Many scientists think that burning fossil fuels also increases the temperature of the earth． To reduce the use of fossil fuels． scientists are experimenting with hydrogen-powered (氢化发动的) cars． These cars don’t pollute the air like gas-powered cars．
Some scientists guess that by 2025, fossil fuels will run out．When people can no longer use gasoline， they may use fuel cells instead． Fuel cells use hydrogen to create energy． People do not need to worry about hydrogen running out， because it is renewable and replaceable．
In Washington， D.C.， a few people drive cars that run on fuel cells． When these cars need more energy, drivers can go to a hydrogen pump．The first hydrogen pump for the public opened in November 2004， marking an important step toward a cleaner environment．
what can we learn from the passage?
A．Fossil fuels don’t pollute the air．
B．Hydrogen-powered cars make less pollution．
C．Many drivers are driving hydrogen-powered cars．
D．We can find many hydrogen pumps in the USA．
How long may people still be able to use fossil fuels?

A．Twenty years．	B．Over thirty-eight years．
C．More than ten years．	D．About seventeen years．

Which of the following is not mentioned?

A．Scientists are producing more hydrogen-powered cars．

B．Some people drive fuel-cell cars in Washington．

C．Fossil fuels come from plants and animals．

D．We can learn about environmentally friendly technology from Earth Day activities．

When do fossil fuels pollute the air?

A．When we use them to create gasoline．

B．When people get them from the underground．

C．After being burned to get energy．

D．After getting them from a hydrogen pump．

Because hydrogen is renewable， we don’t need to worry that ________．

A．it will be used up	B．it can be used for creating energy
C．it will pollute the environment	D．it will be cleaner