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.

    Devon, 17, is used to paying her own cell phone and car expenses. But lately it's been harder. The family she baby-sits for hasn't been calling as much as usual and she couldn't find a job over the summer. Devon's dad said it's a sign of the tough economy. He told her he's feeling the pinch too and that he had to use her college fund to pay the loan(货款).

    This kind of money troubles isn't strange to common families these days. In fact, it's hard to avoid news about the economy on the screen of the TV or the computers recently. It can seem a bit worry and some families are hit really hard.

    For most people, the big problem is that things cost more at a time when they have less money to spend. But higher prices aren't the only problem. Many people are having a tough time making payments on some types of home loans.

    Therefore, some families are cutting back on what they spend.  For example, eating out less, staying home instead of going on vacation, moving to a less expensive house and so on.

    However, as discouraging as things may seem now, the good news is that the economy always gets back on track after a while. Jobs may be hard to find, but the slow economy can open up new opportunities. The couple Devon babysat for might cut back on evening's out, but they could be interested in hiring her for after-school care. Perhaps it's time to sell her old toys and baby gear (设备)in the basement(地下室) or help others sell these items online if she is good at it. She could charge them a fee to sell their old stuff(东西).

    Native to America, the cane toad (癞蛤蟆) was introduced to Northern Queensland 70 years ago to control sugarcane beetles (甘蔗害虫). The toads failed in that duty but spread across Queensland and into neighboring northern areas.

    Now it calmly invades(侵略) the stats of Western Australia and New South Wales ( NSW). NSW wildlife experts fear the amphibians － which have poisonous backs that kill hungry predators (食肉动物) 一will have a terrible effect on native animals.

    Those fears may be about to be realized. Australia's leading government research body, the Commonwealth Science and Industry Research Organization (CSIRO), forecasts that a rise in average temperatures will make NSW an ideal living place for the cane toads.

    Tony Robinson, head of CSIRO's Wildlife, Pests, and Diseases Program, said climate change is increasing the amount of suitable living place for the cane toads.

    “With climate change, the cane toads might go down as far as Sydney and some areas of Western Australia,” Robinson said.

Recent estimates put the pace of the toads' westward march at nearly 17 miles (27 kilometers) a year and slightly slower from north to south.

    “More southerly (南部的) cities, such as Melbourne and Adelaide, would likely remain too cold and dry to ever suit the toads,” Robinson noted, “but Perth could expect cane toads in five years' time.”

    Sydney could see their arrival in the next 20 years.

    Robinson said there is no method that will keep the toads under control.

    The cane toads already cover at least half of Queensland and most of the northern country. The toads are believed to number in the billions.

    A Venezuelan virus was tried in the 1990s but had to be given up after it was found to also kill native frog species. Scientists and governmental bodies believe a national approach is needed.

    The main threat the toads cause to species such as dingoes, and crocodiles is the poison contained in glands (腺) on each of their shoulders. The poison sprays out when the toads are threatened or handled roughly. The poison is made up of 14 different chemicals.

    Cane toads also compete, and usually win, the hunt for food and living space.

    "”If the government and other states combine resources, I believe we can achieve a very practical biological-control research program,” Bums said.

    It was not yet eleven o'clock when a boat crossed the river with a single passenger who was lucky to be able to cross the river at that unusual hour by promising to pay some extra money. While the youth stood in the light place searching his pockets for money, the boatman lifted a lamp, with the help of which, together with the newly risen moon, he took a careful look at the stranger. He was a young man of about eighteen years, clearly country brought up, and was, as it seemed, on his first visit to town. He was wearing a rough grey coat, which was in good shape, and which had seen many winters before this one. The jacket under his coat was made of leather and trousers fitted tightly to a pair of strong legs; his stockings of blue yarn(毛绒) must have been the work of a mother or sister, and on his head was a hat, which in its better days had perhaps protected the grayer head of the young man's father. In his left hand was a walking stick, and on his strong shoulders hung a leather bag. Brown hair, well-shaped features, bright, cheerful eyes were nature's gifts. The youth, whose name was Robin, paid the boatman, and then walked forward into the town with a light step, as if he had not already traveled more than thirty miles that day. As he walked, he looked around as eagerly as if he were entering London or New York instead of the little city in New England.

    Andreea, 18, from Romania, sent a photograph of the view from her window and included a brief (简短的）apology: “Sorry, this picture is plain and boring. No one would like it.”

    At home in New Jersey, US, Coreen Burke, 16, clicked on the same image in her inbox. She saw a village with its old houses, and a distant chimney puffing smoke.

    “Isn't this amazingly different from my country?” she thought to herself.

    Burke saw potential in that photo. She posted it to her blog, Outside My Window，which features a daily snapshot (快照）of someone's window view from different people around the world.

    The concept (理念）is simple: We can all relate to the act of staring through a pane of lass (一块玻璃)，onto the scene on the other side,

    “Maybe if we understood the way people from all over the world live,” she added, “we would get along better than we have been lately.”

    On the sit，Can see Frederic's window in the south of France, looking out on sailboats anchored in a tranquil  harbor(宁静的港湾).0r Virginia's view in Canada, a winter scene with trees laced in white.

    Like most high school students, Burke has yet to travel the world. But she hopes to someday collect many stamps in her passport,starting in Greece and India. In the meantime, however, she's devoting herself to her website.she posted the first window view from Switzerland, a sunset captured (拍摄）by an 18-year-old.Then others came flowing in by email, up to seven a day, from as far as Kazakhstan and Indonesia.

    Contributors are marked on a map on her bedroom wall: A blue dot indicates (表示）their country and a pink dot shows their city, if they provide it. The most responses have come from Europe - Estonia, Poland, Italy, Germany and Sweden, to name a few. She is crossing her Angers that she 11 receive a photo from Africa or Antarctica, which are unrepresented so far.

    And while Burke's become a cyber crusader (斗士）for appreciating the beauty outside our own windows, it will probably come as a surprise to learn that she doesn't actually have a window in her own bedroom. But with the views out of other people's she can enjoy whenever she wants to, she surely doesn't mind.

    Want a wonderful travel in London? Don't miss the following!

    Cartoon Museum

    This highly entertaining London tourist attraction covers the history and development of British cartoons from the 18th century to the present day. You can find a detailed collection of all types of cartoons in this museum including caricatures (讽刺漫画) and rare examples of cartoon art: it's an ideal place to entertain kids of all ages as well as a serious collection for animation enthusiasts.

    There are over nine hundred pieces on exhibit and the museum regularly holds events where both children and adults can participate. Booking for these events is recommended due to the popularity year round of this London Museum.

    Telephone: 020 7580 8155

    Chislehurst Caves

    Chislehurst in London is home to chalk caves that were mined by hand for over 8,000 years. A tour of these caves is an exciting way to see how British people have impacted on their environment over thousands of years.

    Telephone: 020 8467 3264

    The Old Operating Theatre Museum

    The Old Operating Theatre Museum is one London museum offering a fascinating insight into the medical profession of the past. This 300-year old herb garret (阁楼) is Britain's only surviving operating theatre, with a wooden operating table and an observation stand, from which visitors can witness surgery performed.

    Telephone: 020 7188 2679

    Curzon Mayfair Cinema Museum

    Recently voted one of London's best cinemas by Time Out readers, the Curzon Mayfair cinema is everything you would expect from this particular part of town: luxurious (奢华的) and tasteful. Showing mostly art-house and independent films, the Curzon Mayfair is unique in the world of London cinema for its role in screening these films for industry and press.

    Telephone: 033 3321 0104