Number sense is not the ability to count. It is the ability to recognize a 1 in number. Human beings are born with this ability.2, experiments show that many animals are, too. For example, many birds have good number sense. If a nest has four eggs and you remove one, the bird will not3. However, if you remove two, the bird4leaves. This means that the bird knows the5   between two and three.

    Another interesting experiment showed a bird's6number sense. A man was trying to take a photo of a crow(乌鸦)that had a nest in a tower, but the crow always left when she saw him coming. The bird did not7until the man left the tower. The man had an8.He took another man with him to the tower. One man left and the other stayed, but they did not9 the bird. The crow stayed away until the second man left, too. The experiment was10with three men and then with four men. But the crow did not return to the nest until all the men were11.It was not until five men went into the tower and only four left that they were12 able to fool the crow.

    How good is a human's number sense? It's not very good. For example, babies about fourteen months old almost always notice if something is taken away from a 13 group. But when the number goes beyond three or four, the children are14fooled.

    It seems that number sense is something we have in common with many animals in this world, and that our human 15 is not much better than a crow's.

    Elephants practice altruism (利他主义). An Indian elephant called Chandrasekharan lifted poles off a truck as it moved along, and placed them in 1 . When Chandrasekharan came to one hole dug in the ground, he 2 to put the pole in. 3 , the owner checked and discovered a dog sleeping in it. Only when the dog was 4 would Chandrasekharan put the pole in. This sort of 5 is typical of elephants.

    Elephants really do have long 6 . Elephants eat an incredible variety of foods and need to cover large distances to get it. They need to know 7 to go at what time of year. They learn this and 8 it. They also have 9 communication and societies. They need to remember all the different individuals' 10 and smells so as to be socially adept(精通的). The old saying, “An elephant never 11 ,” is fairly true.

    I once had a love-hate relationship with an elephant in Zimbabwe in 1991. Every day I'd 12 out of the front gate and an elephant would attack my vehicle. And every day I'd rev(加速) my engine and  13 the door and tell him to get away and then we would go our 14 ways. Every single day this happened without 15 . If other vehicles came and went he would 16 them and then go for mine.

    One day I went out in a(n) 17 vehicle, stopped nearby and watched for a while. The wind changed, and he caught my smell. 18 , he recognized me as usual.

    More recently it has been 19 that spindle neurons(纺锤体神经元)play an important role in the development of 20 behavior. Spindle neurons are found in the brains of humans, great apes, dolphins and elephants.

    Sometimes called Amazonia, the rainforest of the Amazon River basin is the largest in the world. It stretches (延伸) across more than half of Brazil and parts of seven other South American countries (and French Guiana). With a land area of 2.7 million square miles, the Amazon rainforest is almost two thirds the size of the US.

    Rainforests are important to the health of the entire planet. Often called "the lungs of the planet", the Amazon rainforest, with its rich plant life, stores carbon dioxide while giving out the oxygen we need to survive.

    At one time, rainforests covered 14 percent of Earth's surface. Deforestation has reduced that figure to 6 percent today. Much of the loss has been in the Amazon.

    Fortunately, over the years, Brazil has also become a world leader in rainforest preservation. A law called the Forest Code, originally passed in 1965, requires the Amazon's farmers to protect 80 percent of their land from farming. And democratic governments beginning in the early 1990s began to enforce it seriously.

    Efforts to save the Amazon increased under President Luiz Inacio Lula da Silva (2002—2011). Brazil set aside about 150 million acres of the rainforest, an area about the size of France, for protection. Deforestation fell by 74 percent between 2004 and 2009.

    Other countries of the Amazon have also done their parts. This year, Peru created a forest reserve about the size of California's Yosemite National Park.

    Earthquakes are1; thousands of them happen each day. But most are too weak to feel. During a 2 earthquake, there is often a great noise first. Then the earth3 terribly and many houses 4 down. Railway tracks break and trains go 5 lines; a great many factories are 6 ; thousands of deaths are caused, and many more lose homes... 7 the great damage and deaths caused by the earthquake 8 , other disasters such as fires often 9 . More buildings are destroyed and more 10 caused.

    It is well known of the 11 of a possible earthquake, and for centuries man has been making researches on earthquakes. More than 2,000 years ago, 12, a Chinese scientist named Zhang Heng 13  a machine which could find out from which 14the seismic waves had come, and this machine is still  15 by scientists today. Now we know much more about earthquakes and  16 they happen, but we still cannot 17 exactly when and where an earthquake will happen, and cannot 18 it from happening. So earthquakes are among the 19 disasters in the world.

    No one can stop natural earthquakes. 20 , scientists can help stop earthquakes destroying whole cities and causing too many deaths.

    For centuries, Beijing has been one of China's most important cities. 1a place for emperors and officials, today it is an international city and a popular tourist2. People from all over the country are moving to Beijing to 3 jobs and opportunities as this exciting city is a place where dreams can come true. Throughout the city, 4 dressed business people 5for their offices, mobile phones held to their ears and visitors can only watch and imagine the deals and 6being made at that very second.

    Beijing's streets provide a fascinating 7of the past and the present. In tea houses, groups of old men play chess 8the Macdonald's next door is filled with laughing teenagers sipping milkshakes. Walking through the broad streets 9with designer stores and multi-storey skyscrapers, you can 10 a turn and suddenly find yourself in a century's old 11 where a fruit seller chats happily to an old woman sitting in the sun. Many of the road signs and advertising billboards are now in 12, making Beijing more 13to foreigners. Public transport is efficient, new businesses are14, and every modern convenience and international brand is15in this booming global city.

    Beijing has some of China's most stunning 16. Visitors often come to Beijing with the single 17to see the Great Wall, one of the ancient wonders of the world, but once they've arrived, they realize that this is only one of the city's 18. In fact, what visitors ever seem to only19about Beijing, is that they simply20time before seeing it all.

项。

    Rabbit Island is a tiny and remote island off  northern Michigan's Keweenaw Peninsula.Its

    1 nature is the perfect destination for artists to come and 2 their creativity. New Yorker Rob Gorski 3 the island in 2010, who wanted to protect its natural state. He also saw a(n)  4 to create a setting where artists could get close to 5 and create their great works.

    Gorski set up the Rabbit Island Foundation, whose main goal is to host artistic 6 during the summer while also teaching and 7 conservation.

Artists, with the 8 that the island should largely remain untouched, are 9 to a two-week period of reflective engagement in a wilderness unlike anywhere else in the world. They 10 a"leave no trace " policy. Small solar panels are used to generate electricity and buildings are simple with nothing 11 left in place. " Rabbit Island exists to encourage the community to 12 the most fundamental part of our age — the environment and the human relationship to it. We challenge artists to take 13 and create bold works challenging the assumptions of the landscape created by previous 14, said Gorski.

    Most artists say they have a better understanding and  15 of nature after the experience, which, in turn, gives them many creative inspirations.