阅读理解。

    There is no question that fewer teenagers are on the roads in the US.

    In 1978, 50% of 16-year-olds had got their first driving licences. In 2008, according to the US Transportation Department, it was just 30%. The number of those aged 19 and under with driving licences has also been declining since 1978, when 11,989,000 had licences. In 2010, it was 9, 932,441, or 4.1% of American drivers.

    In the UK, 683,273 teenagers have driving licences—just 1.85% of total licence holders, according to Department of Transport figures from September 2010.

    But the decline in the US may have more to do with tougher tests and the introduction of the new rule in many states, which force drivers aged under 16 to be with licensed drivers of 21 years and older when driving.

    In recent years, the annual number of journeys being made by American drivers of all ages has declined clearly for the first time ever. Car use began falling in 2007, when average petrol prices almost doubled to $ 4.12 a gallon, and the economy became worse.

    But there are signs that it is getting back to normal and America remains a country on wheels. It has a higher number of cars per head of population than any other country in the world.

    “Cars will always be a popular means of transportation in America. You have to take into consideration some places don't have access to public transportation. Cars are the only way some people can get around,” says Kristin Nevels. This makes driving necessary in some rural states, where about twice as many teenagers are on the road than in big cities.

    “An apple a day keeps the doctor away.” Similarly, if we drink a little more water every day, we may find that we need to go to the doctor a lot less often. A healthy diet is made up of water and a great many different kinds of foods. We know that healthy foods like fruits, vegetables and fish, are important as they provide us with energy and fiber, without giving us too much fat and sugar. But why is water important?

    The human body needs water to survive. Water is important as it carries poisons and waste out of our bodies. However, doctors advise us to drink plenty of water, much more than the small amount we need to stay alive.

    Some doctors believe that water is important for our health in all kinds of ways. They believe that a great many illnesses and health problems start as a result of dehydration(脱水)—a lack of water in the body. Most people are dehydrated at least some of time, although they probably don't know it. It is surprising to learn that if we feel thirsty, we are already in the first stage of dehydration. In fact, we are advised to drink water before we feel thirsty.

    These doctors think that health problems such as headaches, high blood pressure and asthma(哮喘) could be helped if people drink more water. They also believe that drinking more water can help people who are overweight. Water contains no calories so it will not make us put on weight. If we drink water, we will probably drink less sugary soft drinks such as Coca-cola. Doctors also believe that drinking more water may stop people from overeating. They say that many people think that they are hungry when they are, in fact, thirsty. Doctors suggest, therefore, that we eat less food and drink more water. There are still many health problems that cannot be solved by drinking water, so we should not stop going to seeing the doctor completely. However, if we make a decision to drink water every day, we may find that we need to go to the doctor a lot less often.

    Earthquakes happen without warning(前兆). They can happen any time of a day, at any point during the year. But don't worry because most are so weak that they cannot be felt. Only a few big ones hurt people. However, it's important to know what to do when an earthquake is happening.

    Do NOT go outside. You could get injured from falling glass or parts of buildings. If you are outside, stay away from buildings and power lines (输电线).

    Stay under a desk, table, or other strong furniture. Hold on to it. Or stay in a corner of the building. Cover your face and head with your arms and cover your mouth with a towel or clothing. Stay inside until shaking stops and it is safe to go outside.

    Keep away from windows, pictures or advertisements on the wall or the building, and anything else that could fall and hurt you. Most people get injured by falling things during an earthquake, not by the shaking itself.

    Also keep away from a fire. You could fall down and burn yourself on the fire.

    If you are driving when an earthquake happens, stop the car if it's safe. Stay inside your car until the earthquake stops, and don't drive near bridges. Try not to stop by power lines or trees. These could fall and hurt you.

    Breathing dirty air comes at a high price. Air pollution lowers the average life spans (寿命) by a year worldwide and in more polluted parts of Asia and Africa, dirty air shortens lives up to twice that much. Scientists shared their new findings in Environmental Science & Technology Letters. The study used data gathered in 2016 as part of a project known as the Global Burden of Disease and was the first major country-by-country look at the connection between the length of life and what's known as fine PM.

    Air pollution has been linked to many health problems. Most earlier studies had looked at how tiny air pollutants affected rates of illness or death. Joshua Apte is an environmental scientist at the University of Texas at Austin. By looking at life expectancy (预期寿命), his team had hoped to make the threat easier to understand. PM2.5 is what scientists call tiny particles (颗粒) of pollution in the air. Higher levels of PM2.5 can cause health problems and cut months, if not years, from the average length of life. This analysis shows how pollution affects life expectancy in different parts of the world.

    The World Health Organization (WHO) recommends limiting PM2.5 to 10 micrograms per cubic meter of air. Apte's group calculated how holding pollution to this low level would help people. In countries with very dirty air, meeting this standard would lengthen people's lives. However, in countries whose air already meets this standard, the study shows no gain in life expectancy. In other words, meeting the WHO standard won't reduce health costs resulting from dirty air because even below 10 micrograms per cubic meter, pollution still causes serious risks. Meanwhile, the scientists compared how other threats including smoking and cancer shorten the length of life across the globe.

Going to concerts and live performances is a lot of fun. As a teen, you'll want to prepare for the event far in advance in order to ensure that your concert experience is enjoyable.

Check to make sure that the concert venue(场所) is for all ages.

Some venues, particularly those that serve alcohol, will only allow entry for guests who are over 21 years old. {#blank#}1{#/blank#} If you buy a ticket and get turned away at the door, you likely will not get your money back.

Ask your parents for permission.

{#blank#}2{#/blank#} Have a conversation with your parents to figure out how you will travel to and from the concert, and talk about ground rules for staying safe at the event.

Find a friend to go with.

For your safety, it's best not to attend concerts alone. {#blank#}3{#/blank#} If you're having trouble finding company, consider posting on Facebook, Twitter, or Instagram to see if other people in your social network are interested.

Buy tickets.

If the concert is for a popular band, figure out exactly when the tickets go on sale. {#blank#}4{#/blank#}Ticketmaster. com sells tickets for bigger shows, but if you're going to a smaller show, look online at the venue's website for information on how to buy tickets.

Research venue policies and regulations.

Find the venue's web page to get a sense of what to expect, and to avoid any problem on the day of the concert. You should know how early the doors will open. {#blank#}5{#/blank#}