Traffic problems are an everyday concern in many cities，including Washington，DC．A growing number of Washingtonians are turning to bicycles to get to and from work．In fact，the number of commuters who use bicycles has doubled in the city since 2007．

    Ralph Buehler teaches urban planning at the Virginia Polytechnic Institute and State University，popularly known as Virginia Tech．He has written a book about urban biking，calledCity Cyclin . g．He says there is a reason why urban bike tiding is now becoming more popular．

    “Over the last 60 to 70 years，cities in America have adapted to the automobile．”

    “Most cities took advantage of the money coming for the interstate highway system，from the federal government，  starting in 1956．There was a 90 percent federal match(补贴)so the cities only had to put up 10％．It was very tempting．”

    In the years after World War Two，many Americans moved to suburban communities，just outside major cities．They decided to travel great distances to and from work in exchange for a home in the suburbs．Their cars became a symbol of freedom．

    But today，many people believe they can save money by living in the city．

    Greg Billing is with the Washington Area Bicyclist Association．“When a person makes a change from using a car to using a bike，he／she is saving anywhere between 8 or $9，000 a year．”

    Ralph Buehler says governments save money when people use bicycles．“Building bicycling facilities is much cheaper than building and maintaining road facilities or public transport．”

    Washington，DC has also taken steps to protect bike riders．It approved a safe passing law and created areas on the road between cars and bikes．

    The United States Census Bureau says 4％of the city's workers ride to work by bike．The only city on the East Coast with more bike commuters is New York．

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    Put on your sunglasses and enjoy the island, the sun and the blue sea. Malta combines (结合) learning English with the Mediterranean way of life: you will have language course and a great holiday at the same time,

    Your language course    Our school lies in Sliema, only a few meters from the sea, the beach road and cafés. The school is in an old Maltese building. Our teachers use a modern teaching method and you will learn English quickly.

    The leisure (休闲) programmes    Our school and team leaders organize varied leisure programmes. There will be a welcome party on your first day. You will also take part in beach volleyball, and beach parties. Other activities include: Discos, visit to Popeye Village, Water Park, bowling, cinema, ice skating (different prices).

    Accommodation (住宿) Family    You will live in friendly host families that the school has known for years. All families are near the school (20 minutes on foot or by bus).

    Supervision (监督)    Our team of friendly teachers, team leaders and host families will always be there for you. There is also an emergency phone number for parents and students.

    Dear parents, please note that there are periods of time when your children are unsupervised, for example on the way to school. We are happy to discuss any questions you may have. Please contact us by phone or email.

    Whether in the home or the workplace, social robots are going to become more common in the next few years. Social robots are about to bring technology to the everyday world in a more humanized way, said Cynthia Breazeal, chief scientist at the robot company Jibo.

    While household robots today do the normal housework, social robots will be much more like partners than tools. For example, these robots will be able to tell when someone is happy or sad. This allows them to respond more properly to the user.

    The Jibo robot, arranged to ship later this year, is designed to be a personalized assistant. You can talk to the robot, ask it questions, and make requests for it to perform different tasks. The robot doesn't just give general answers to questions; it responds based on what it learns about each person in the household. It can do things such as reminding an elderly family member to take medicine or taking family photos.

    Social robots are not just finding their way into the home. They have potential(潜在的) applications in everything from education to health care and are already finding their way into some of these areas.

    Fellow Robots is one company bringing social robots to the market. The company's “Oshbot” robot is built to assist customers in a store, which can help the customers find items and help guide them to the product's location in the store. It can also speak different languages and make recommendations for different items based on what the customer is shopping for.

    The more interaction the robot has with humans, the more it learns. But Oshbot, like other social robots, is not aimed to replace workers, but to work together with other employees. “We have technologies to train social robots to do things not for us, but with us,” said Breazeal.

    The largest genetic study of mosquitoes has found their ability to resist insecticides(杀虫剂) is evolving rapidly and spreading across Africa, putting millions of people at higher risk of contracting malaria(疟疾).

British scientists who led the work said mosquitoes' growing resistance to control tools such as insecticide-treated bed nets and insecticide spraying, which have helped cut malaria cases since 2000, now threatens "to disturb malaria control" in Africa.

    "Our study highlights the severe challenges facing public efforts to control mosquitoes and to manage and limit insecticide resistance," said Martin Donnelly of the Liverpool School of Tropical Medicine, who worked on the study with a team from Britain's Wellcome Trust Sanger Institute.

    Latest World Health Organization (WHO) data show that 216 million people were infected last year with the malaria parasite(寄生虫), which is transmitted by blood-sucking Anopheles mosquitoes. The disease killed 445,000 people in 2016, and the majority of them were children in sub-Saharan Africa.

    To understand how mosquitoes are evolving, the researchers sequenced the DNA of 765 wild Anopheles mosquitoes taken from 15 locations across eight African countries. Their work, published in the journal Nature on Wednesday, created the largest data resource on natural genetic variation for any species of insect.

    Analyzing the data, the scientists found that the Anopheles gamblae mosquitoes(冈比亚疟蚊)were extremely genetically diverse compared with most other animal species. This high genetic diversity enables rapid evolution, they said, and helps to explain how mosquitoes develop insecticide resistance so quickly.

    The data also showed the rapid evolution of insecticide resistance appeared to be due to many previously unknown genetic variants(变体)within certain genes. The scientists said these genetic variants for insecticide resistance were not only emerging independently in different parts of Africa, but were also being spread across the continent by mosquito migration.

    Michael Chew, an expert at Britain's Wellcome Trust global health charity which helped fund the research, said the finds underlined the importance of pushing scientific research ahead to control malaria.

Global efforts to control malaria through effective vaccine, insecticides and the best drug combinations require urgent, united action by scientists, drug companies, governments and the WHO.

    Many people have long dreamed of being able to fly around as simply as riding a bicycle.

    Yet the safety and strength of a flying bike was always a big problem. Over the past 10 years' developments in technology have moved the dream of personal flying vehicle closer to reality. Now, two groups of inventors say such vehicles may be available very soon.

    Grant Stapleton from Malloy Aeronautics says the Hoverbike, which is able to get in and out of small spaces very quickly, will be a truly personal flying vehicle." It can be moved across continents very quickly because it can be folded and packed," he adds.

    Mr. Stapleton says safety was the company's main concern when developing the Hoverbike, He says the designers solved the safety issue by using overlapping rotors (折叠旋翼)to power the vehicle. The company is testing both a one-third size model and a full-size prototype (原型))of the Hoverbike.

    Inventors say their Hovebike will most likely be used first by the police and emergency rescue teams.

    In New Zealand, the Martin Aircraft Company is also testing a full-size prototype of its personal flying bike, called Jetpack. It can fly for more than 30 minutes, up to 1,000 meters high and reach a speed of 74 kilometers per hour.

    Peter Coker is the CEO of Martin Aircraft Company. He said Jetpack" is built around safety from the start" In his words, reliability is the most important part of it. We have safety built into the actual structure itself very similar to a Formula One racing car."

    Jetpack uses a gasoline-powered engine that produces two powerful jet streams. Mr. Coker says it also has a parachute (降落伞)that can be used should there be an emergency.

    "It opens at a very low altitude and actually saves both the aircraft and the pilot in an emergency," he adds.

    An earthquake is one of the most common natural disasters. It may cause great damage. So it is wise to learn some simple safety tips to protect yourself or your family members.

    Fragile items like those made of glass are easily broken and should usually be placed on a lower surface, near the ground instead of placing them in the cupboards higher up. Never place them near your bed, sofas and other furniture where you would be sitting or lying down. When there is a strong movement, these pieces will fall on the floor directly and not on you.

    There is a strong chance of short circuits (短路) and fire during an earthquake. Make sure you turn off electrical connections and gas immediately when an earthquake happens.

    During an earthquake, lie beneath an object that is not easily damaged. Do not go near objects that could directly fall on you. Never use the elevator to go down. Stay inside until the shaking stops and it is safe to go outside. Research has shown that most injuries happen when people inside buildings try to go out. Use the staircases at all times.

    If you are outdoors, do not take shelter under a tree, streetlights, electric poles or tall buildings. If you are driving, stop your car and stay in a safe place. Do not park your car under a tree or any tall object.

    If trapped in debris (瓦砾堆), cover your mouth with a handkerchief or clothing. Tap on a pipe or the wall so that rescuers (营救人员) can find you. Use a whistle (哨子) if one is available. Never shout for help. Shouting can cause you to breathe in dangerous amounts of dust. Do not light a match because you may burn yourself. Do not move about or kick up dust.