Mosquitoes have an extraordinary ability to find humans far away and fly straight to their skin. Mosquitoes can do more than cause an itchy (发痒的）wound. Some mosquitoes spread several serious diseases, including Dengue, yellow fever and malaria.

    Over one million people worldwide die from these diseases each year. New research now shows how mosquitoes choose who to bite.

    Mosquitoes need blood to survive. They are attracted to human skin and breath. They smell the carbon dioxide gas, which all mammals breathe out. This gas is the main way for mosquitoes to know that a warm-blooded creature is nearby.

    But mosquitoes also use their eyes and sense of touch. Michael Dickinson is a professor at the California Institute of Technology. His research shows how these small insects, with even smaller brains, use three senses to find a blood meal.

    Michael Dickinson's team used plumes—a material that rises into the air of carbon dioxide gas into a wind tunnel (隧道). They then used cameras to record the mosquitoes. The insects followed the plume.

    Then, the scientists placed dark objects on the lighter colored floor and walls of the tunnel. Mr. Dickinson said, at first, the mosquitoes showed no interest in the objects at all. “What was quite surprising is that the mosquitoes fly back and forth for hours. These are hungry females and they completely ignore the objects on the floor and wall of the tunnel. But the moment they get a hit of CO₂, they change their behavior quite obviously and now would become attracted to these little visual blobs (斑点).”

    This suggested to the researchers that a mosquito's sense of smell is more important in the search for food. Once mosquitoes catch a smell of a human or animal, they also follow visual signals.

    People who multitask all the time may be the worst at doing two things at once, a new research suggests. The findings, based on performances and self-evaluation by about 275 college students, indicate that many people multitask not out of a desire to increase productivity, but because they are easily distracted and can't focus on one activity. And “those people turn out to be the worst at handling different things,” said David Sanbonmatsu, a psychologist at the University of Utah.

    Sanbonmatsu and his colleagues gave the students a set of tests and asked them to report how often they multitasked, how good they thought they were at it, and how sensation-seeking (寻求刺激) or imperative (冲动) they were. They then evaluated the participants' multitasking ability with a tricky mental task that required the students to do simple mathematical calculations while remembering a set of letters.

    Not surprisingly, the scientists said, most people thought they were better than average at multitasking, and those who thought they were better at it were more likely to report using a cellphone while driving or viewing multiple kinds of media at once. But those who frequently deal with many things at the same time were found to perform the worst at the actual multitasking test. They also were more likely to admit to sensation-seeking and impulsive behavior, which connects with how easily people get bored and distracted.

     “People multitask not because it's going to lead to greater productivity, but because they're distractible, and they get sucked into things that are not as important.” Sanbonmatsu said.

    Adam Gazzaley, a researcher at the University of California, San Francisco, who was not a member of the research group, said one limitation of the study was that it couldn't find out whether people who start out less focused tend toward multitasking or whether people's recognizing and understanding abilities change as a result of multitasking.

    The findings do suggest, however, why the sensation-seeker who multitask the most may enjoy risky distracted driving. “People who are multitasking are generally less sensitive to risky situations.” said Paul Atchley, another researcher not in the group. “This may partly explain why people go in for these situations even though they're dangerous.”

    Good afternoon, and welcome to England. We hope that your visit here will be a pleasant one. Today, I would like to draw your attention to a few of our laws.

    The first one is about drinking. Now, you may not buy alcohol in this country if you are under 18 years of age, nor may your friends buy it for you.

    Secondly, noise, Enjoy yourselves by all means, but please don't make unnecessary noise, particularly at night. We ask you to respect other people who may wish to be quiet.

    Thirdly, crossing the road. Be careful. The traffic moves on the left side of the road in this country. Use pedestrian crossings and do not take any risk when crossing the road.

    My next point is about litter（throwing away wasted material in a public place）. It is an offence to drop litter in the street. When you have something to throw away, please put it in your pocket and take it home, or put it in a litter bin.

Finally, as regards smoking, it is against the law to buy cigarettes or tobacco if you are under 16 years of age.

    I'd like to finish by saying that if you requires any sort of help or assistance, you should get in touch with your local police station, who will be pleased to help you.

    Now, are there any questions?

    Something about the four World Famous Statues

    The Little Mermaid

    The statue The Little Mermaid sits on a rock in the Copenhagen harbor at Langelinie in Denmark. Tourists visiting for the first time are often surprised by the relatively small size of the statue. The Little Mermaid is only 1.25 meters high and weighs around 175kg. designed by Edvard Eriksen, the statue was erected in 1913 to commemorate（纪念）the fairy tale The Little Mermaid. The poor lady has lost her head several times but each time it has been restored. Copenhagen officials announced that the statue may be moved further out in the harbor, as to avoid further vandalism(故意破坏)and to prevent tourists from climbing onto it.

    David Statue

    David is a masterpiece of Renaissance sculpture sculpted by Michelangelo from 1501 to 1504. The 5.17 meter marble statue portray the hero after his victory over Goliath, Michelangelo chose to represent David before the fight contemplating(沉思)the battle yet to come. To protect it from damage, the famous statue was moved in 1873 to the Accademia Gallery in Florence in Italy, where it attracts many visitors. A replica was placed in the Piazza della Signoria, at the original location.

    Great Sphinx

    Located at the Giza Plateau near Cairo in Egypt, the Great Sphinx is one of the largest and oldest statues in the world, but basic facts as who was the model for the face, when it was built, and by whom, are still debated. It is the largest monolithic(独块巨石的)statue in the world although it is considerably smaller than the pyramids around it. Despite conflicting evidence and viewpoints over by the years, the traditional view held by modern Egyptologists at large remains that the Great Sphinx was built in approximately 2500 BC by the Pharaoh Khafre, the supposed builder of the second pyramid at Giza.

    Statue of Liberty

    The Statue of Liberty, a gift from the people France to celebrate the centennial of the signing of the United States Declaration of Independence, stands upon Liberty Island and is one of the most famous symbols in the world. It represents a woman wearing a stole, a radiant crown and sandals, trampling a broken chain, carrying a torch her raised right hand and a tabula ansata tablet in her left hand. The construction of the statue was completed in France 1886 until the jet age, it was often one of the first glimpses of the United States for millions of immigrants.

    A recent university study found that current electric cars could be used for 87% of daily car journeys in the US. That figure could rise to 98% by 2020.

One hurdle to the widespread adoption of electric cars has been “range anxiety” —drivers' concerns about running out of petrol on a journey. While petrol stations are conveniently located across national road systems, the necessary network of electric charging stations is still being developed. In fact, charging points are becoming increasingly common throughout the USA.

    Attitudes towards electric vehicles have changed quite considerably over the last few years. Not that long ago, electric cars met with doubt, and their high price drove customers away. Thanks to improvements in battery capacity(电池容量), recharging times, performance and price, the current generation of electric cars is starting to persuade critics.

    As well as progress on the road, electric vehicles are taking to the sea and sky. Electric boats are among the oldest electric vehicles, having enjoyed several decades of popularity from the late 19th to the early 20th century before petrol-powered outboard motors took over. Now, the global drive for renewable energy sources is bringing electric boats back. Steps towards electric planes are also being made, with Airbus and NASA among the organizations developing and testing battery-powered planes. The experiments could soon make electric flight a reality.

    Electric vehicles do not produce any emissions(排放物). Were the US to act on the study's findings and replace 87 percent of its cars with electric vehicles, it would reduce the national demand for petrol by 61 per cent. However, because of the production processes and the generation of electricity required to charge these vehicles, they cannot claim to be completely emission-free. Even so, as many countries continue to increase their use of renewable energy sources, electric vehicles will become even cleaner.

Music

    Opera at Music Hall: 1243 Elm Street The season runs June through August, with additional performances in March and September. The Opera honors Enjoy the Arts membership discounts. Phone: 241 ­2742.

    http://www.cityopera.com

    Chamber Orchestra: The Orchestra plays at Memorial Hall at 106 Elm Street, which offers several conceits from March through June. Gall 723­1182 for more information.

    http://www.chamberorch.com.

    Symphony Orchestra: At Music Hall and Riverbend. For ticket sales, call 381­3300. Regular season runs September through May at Music Hall in summer al Riverbend.

    http://www.symphony.org/honie.asp.

    College Conservatory Of Music (CCM): Performances are on the main campus of the university, usually at Patricia Cobbett Theater. CCM organizes a variety of events, including performances by the well­known LaSalle Quarter, CMM's Philharmonic Orchesira, and various groups of musicians presenting Baroque through modem misic. Students with I.D. cards can attend the events for free. A free schedule of events for each term is available by coiling the box office at 556­4183.

    http://www.ccm. uc.edu/events/calendar.

    Rivebent Music Theater.6295 Kellogg Ave« Large outdoor theater with the closest seats under cover (price difference). Big name shows all summer long! Phone:232­6220.

    http://www.riverbendmusic.com