Each passenger needs a farecard to enter and go out .Up to two children under age five may travel free with a paying customer .

    Farecard machines are in every station .Bring small bills because there are no change machines in the stations and farecard machines only provide up to $5 in change.

    Get one ticket of unlimited Metrorall rides with a One Day Pass .Buy it from a farecard machine in Metro stations .Use it after 9:30 a,m. until closing on weekdays , and all day on weekends and holidays .

    Hours of service

    Open 5am  Mon-Fri             7a.m  Sat-Sun

    Open midnight Sun-Thur.

    Last train times vary .

Train times Posted in stations

    Metrobus

    When paying with exact charge , the fare is $1.35.When paying with a SmarTripⓇcard , the fare is

    1.25.

    Fares

    Senior citizens 65 and older and disabled customers may ride for half the regular fare .On Metrorail and Metrobus , use a senior/disabled farecard or Smar/Trip Ⓡ card .For more information about buying senior .disabled farecard , SmarTripⓇcards and passes , please visit MetroOpensDoors .com or call 202-637-7000and 202-637-8000.

    Senior citizens and disabled customers can get free guide on how to use proper Metrobus and Metrorall services by calling 202-962-1100.

    Travel tips (提示)

    Avoid riding during weekday rush periods –before 9:30 a.m. and between 4and 6p.m.

    If you lose something on a bus or train or in a station, please call Lost &Found at 202-962-1195,

    Air travel can be annoying. But research now suggests global warming could make it much worse. To get off the ground in really hot weather, planes may be forced to carry fewer passengers. That might mean a little more space, which would be good. However, it also would make the passengers pay more.

    Average air temperatures around the world are rising because people are polluting the air with an increasing number of greenhouse gases, which, such as carbon dioxide, are a byproduct (副产品) of burning fuels. Those warmer temperatures can influence an airplane's ability to fly because air molecules (分子) spread out more as the air warms. This produces less lift under a plane's wings, so a plane must be lighter to take off in hot weather than on cooler days.

It can even prove too dangerous for some planes to attempt a take-off. A record of June heat wave in the American Southwest, for instance, caused flight cancellations in Phoenix, Ariz. One airline's planes were cleared to operate only up to 47.8 degree Celsius. On June 20, Phoenix reached 48.3℃!

    Radley Horton is a climate scientist at Columbia University. Two years ago, he and his graduate student Ethan David Coffel studied the impact of warming at four U.S. airports and found that warming of track could triple (使成三倍) the number of days when planes face weight restrictions. Later, they explored the impact of rising temperatures on live types of commercial planes flying out of 19 of the world's busiest airports. In the coming decades, as many as one to three out of every 10 flights that take off during the hottest time of day could face weight. That would be equal to taking a dozen people off the plane, the researchers calculated.

    What's the meaning of "dark horse"? It's someone who wins when no one expects it.Han Xiaopeng took China's first gold on snow. He became an Olympic "dark horse" by winning the gold medal in men's freestyle aerial skiing(自由式滑雪空中技巧) at Turin in Italy. He made two almost perfect jumps for the highest score. Han had never won a world gold medal before, let alone(更不用说) in the Olympics!

    "I never thought this would happen," said the 23-year-old. "I feel like I'm in a dream." It's China's second gold medal at the Turin Olympics. But more important, Han's gold was the country's first ever in a snow sport. In 2002, China's Yang Yang won the gold for speed skating at the winter Olympics in Salt Lake City, US.

    That Han's win was unexpected doesn't mean that he didn't work hard.

    Han grew up in Jiangsu Province. Before he started his training on snow, he used to be an acrobat(杂技演员) at a circus. In 1995, a coach found his talent(才能). The coach, Yang Er'qi, said Han had the agility(灵活性) and courage to be a ski jumper. When Yang first took the 12-year-old to northern China, the boy couldn't swim, skate or ski. But he wasn't afraid of the high platform(跳台) and kept on training.

    Han almost left the sport after hurting his knee months before the Salt Lake Games. In that Olympics he only got 24th. "I was hopeless at that time, but my family and the coach stood firmly(坚强地) behind me, helping me through," he recalled.

    Han Xiaopeng worked so hard that he won the gold medal in the Olympics at last. Because of his success, more and more people in China are becoming interested in skiing. We are proud of him and we hope he will have another big success in the next winter Olympics.

    Why is pink or purple a color for girls and blue or brown for boys?

    The answer depends largely on cultural values as well as personal experiences. To the Egyptians, green was a color that represented the hope and joy of spring, while for Muslims, it means heaven. Red is a symbol of good luck in many cultures. In China, children are given money in a red envelope to bring good fortune in the New Year. For many nations, blue is a symbol of protection and religious beliefs. Greek people often wear a blue necklace hoping to protect themselves against evils(灾祸).

    People's choice of colors is also influenced by their bodies' reactions toward them. Green is said to be the most restful color. It has the ability to reduce pain and relax people both mentally and physically. People who work in green environments have been found to have fewer stomachaches.

    Red can cause a person's blood pressure to rise and increase people's appetites(食欲). Many decorators will include different shades of red in the restaurant. Similarly, many commercial websites will have a red “Buy Now” button because red is a color that easily catches a person's eye.

    Blue is another calming color. Unlike red, blue can cause people to lose appetite. So if you want to eat less, some suggest that eating from blue plates can help.

    The next time you are deciding on what to wear or what color to decorate your room, think about the color carefully.

    Grown-ups are often surprised by how well they remember something they learned as children but have never practiced ever since. A man who has not had a chance to go swimming for years can still swim as well as ever when he gets back in the water. He can get on a bicycle after many years and still ride away. He can play catch and hit a ball as well as his son. A mother who has not thought about the words for years can teach her daughter the poem that begins “Twinkle, twinkle, little star” or remember the story of Cinderella or Goldilocks and the Three Bears.

    One explanation is the law of overlearning, which can be stated as follows: Once we have learned something, additional learning experiences increase the length of time we will remember it.

    In childhood we usually continue to practice such skills as swimming, bicycle riding, and playing baseball long after we have learned them. We continue to listen to and remind ourselves of words such as “Twinkle, twinkle, little star” and childhood tales such as Cinderella and Goldilocks. We not only learn but overlearn.

    The multiplication tables (乘法口诀表) are an exception to the general rule that we forget rather quickly the things that we learn in school, because they are another of the things we overlearn in childhood.

    The law of overlearning explains why cramming (突击学习) for an examination, though it may result in a passing grade, is not a satisfactory way to learn a college course. By cramming, a student may learn the subject well enough to get by on the examination, but he is likely soon to forget almost everything he learned. A little overlearning, on the other hand, is really necessary for one's future development.

    At least 12 other murders since 1997 have been linked to an addiction to violent video games. This year, the parents of a 14-year-old murder victim in the UK blamed the killer's addiction to the game Manhunt, causing a government review of legislation (立法) to protect children.

    But is there any scientific evidence that mere games can make children and young adults more aggressive, or possibly have the desire to murder? There is no doubt children are being exposed to more games violence than ever: around a quarter of all games released in the US contain some violence. And the violence is becoming more obvious as increases in computing power make the games look ever more realistic.

    Psychologists think there may be many reasons why violent games are more harmful to children than violent movies. Firstly, players are actively involved in violence, and may begin to use weapons as second nature. Secondly, violent games provide repetitive aggressive experiences that are rewarded by more killing.

    Many studies have shown that people who play violent games regularly are more likely to show high levels of aggression. For instance, in 2000, Craig Anderson of Iowa State University in Ames and his colleague Karen Dill found that people who played violent games were more likely to admit to aggressive behaviour, including attacks or robberies.

    Earlier this year, Krahe and her colleague Ingrid Miller reported a study of 13 to 14-year-old children. More than half had played games recommended only for over-18s. The more violent the games they played, the more they considered physical aggression to be acceptable. Other authors in the same edition report that children who play violent games more likely to argue with teachers and fight with others.

    Experimental studies have also pointed out a possible link. In one, Anderson and Dill asked a group of students to play a violent game, Wolfenstein 3D, while another group played the non-violent Myst. Those who played the violent game were faster to react to aggressive words flashed on screen and appeared more aggressive.

    The issue is controversial, however. Jeffrey Goldstein, a psychologist at the University of Utrecht in the Netherlands and a consultant to some video games publishers, agrees that there is good evidence that children, who are exposed to violent media, including video games, are more aggressive. But he warns it might not be a simple case of cause and effect: aggressive kids might be most attracted to violent games.