Light travels at a speed which is about a million times faster than the speed of sound. In one second, light travels about 300,000 km, but sound travels only 344m. You can get some idea of this difference by watching the start of a race. If you stand some distance away from the starter, you can see smoke come from his gun before the sound reaches your ears. This great speed of light produces some strange facts. Sunlight takes about 8 minutes to reach us. If you look at the light of the moon tonight, remember that the light rays（光线）left the moon 1.3 seconds before they reached you. The nearest star is so far away that the light which you can see from it tonight started to travel towards you four years ago at a speed of nearly 2 million km per minute. In some cases the light from one of tonight's stars started on its journey to you before you were born.

    Thus, if we want to be honest, we cannot say “The stars are shinning tonight.” We have to say, “The stars look pretty. They were shining four years ago but their light has only just reached Earth.”

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    In the sea there are many islands. In its warm waters there are some little ones. We call them “Coral Islands”.

    A coral island is very nice to look at. It looks like a ring of land with tress, grass, and flowers on it. One part of the ring is open to the water. There is a little round lake inside the island.

    If you look into this lake, you will see beautiful coral. You may think they are flowers.

    If you look at a piece of coral, you will see many little holes in it. In each of these holes a very small sea animal has lived . These sea animals make the coral.

    They began to build under the water. Year after year, the coral grew higher and higher.

    At last it grew out of the water.

    Then the sea brought to it small trees and something else. After some years, these things changed into earth. Sometimes the wind brought seeds to this earth. Sometimes birds flew over it and brought seeds to the island.

    The little seeds grew. In a few years there were plants all over the island. In a few more years there were trees growing there.

    So you see, these islands were built little by little. The workers were very small. Do they not teach us a lesson? Can you think what the lesson is?

    Most people agree that honesty is a good thing. But does Mother Nature agree? Animals can't talk, but can they lie in other ways? Can they lie with their bodies and behavior? Animal experts may not call it lying, but they do agree that many animals, from birds to chimpanzees, behave dishonestly to fool other animals. Why? Dishonesty often helps them survive.

    Many kinds of birds are very successful at fooling other animals. For example, a bird called the plover sometimes pretends to be hurt in order to protect its young. When a predator（猎食动物）gets close to its nest, the plover leads the predator away from the nest. How? It pretends to have a broken wing. The predator follows the “hurt” adult, leaving the baby birds safe in the nest.

  Another kind of bird, the scrub jay, buries its food so it always has something to eat. Scrub jays are also thieves. They watch where others bury their food and steal it. But clever scrub jays seem to know when a thief is watching them. So they go back later, unbury the food, and bury it again somewhere else.

    Birds called cuckoos have found a way to have babies without doing much work. How? They don't make nests. Instead, they get into other birds' nests secretly. Then they lay their eggs and fly away. When the baby birds come out, their adoptive parents feed them.

    Chimpanzees, or chimps, can also be sneaky. After a fight, the losing chimp will give its hand to the other. When the winning chimp puts out its hand, too, the chimps are friendly again. But an animal expert once saw a losing chimp take the winner's hand and start fighting again.

    Chimps are sneaky in other ways, too. When chimps find food that they love, such as bananas, it is natural for them to cry out. Then other chimps come running. But some clever chimps learn to cry very softly when they find food. That way, other chimps don't hear them, and they don't need to share their food.

    As children, many of us learn the saying “You can't fool Mother Nature.” But maybe you can't trust her, either.

    Entrepreneur and CEO of Tesla and Space X, Eldon Musk may have a little more time on his hands, as he's leaving his position on the board of the Open Al, according to a blog post.

    The departure is likely the result of Tesla's moving into the field of Artificial Intelligence(AI)，which he said in 2017 would be the “best in the world”and would even be able to “predict your destination, ”Musk will continue to “donate and advise the organization,” Open AI said in a blog post on Feb. 20, adding that “As Tesla continues to become more focused on AI, this will avoid a potential future conflict for Eldon.

    Musk and Y Combiner CEO Sam Altman co-founded the nonprofit enterprise in December2015, its mission is to develop safe artificial general intelligence and ensure those developments are made public. Open AI researchers published a paper on the site ArXiv, org, detailing the possible secure threats that come with“malicious”AI. In fact, Musk has heard the “evil AI”alarm several times, On Aug.11，2017, he warned that artificial intelligence poses a bigger threat to humanity, and he told a gathering of state governors that the government needs to regulate Al before robots start “killing people. ”

    Musk's departure from the Open AI board could mean big things for Tesla. As Eton Goodbye, a financial reporter, noted on Futurism, the move “could signal that Tesla is more deeply committed to their own AI projects than we thought. ”He added, “Those who have had their ears to any rumors (谣言)that Tesla is ready to deliver vehicles capable of Level 5autonomy could take this new Open Al development as a sign that the company is inching closer to that unapproachable goal, ”No company has reached that level of autonomy, which means that a driverless car could navigate any road under any conditions and that all the human “driver” would need to do is to input a destination.

    Staying up late is a potential battle between parents and kids. But the solution could be as simple as changing your meal time.

    Researchers at the University of Surrey, UK, found that delaying (延迟) meals could help change one of the internal (内部的) body clocks. Besides a “master” clock in the brain, there are clocks in other parts of the body. They are usually synchronized (同步的) according to factors including light.

    During the study, researchers tested 10 participants to study the effect of changing meal times on their body clocks. The participants were given three meals – breakfast, lunch and dinner. In the first stage, participants received breakfast 30 minutes after waking. Lunch and dinner followed, after 5-hour intervals (间隔). In the second stage, each meal was delayed by 5 hours. Right after each stage, blood and fat samples (样本) were collected.

    Results showed that later meal times greatly influenced blood sugar levels. A 5-hour delay in meal times caused a 5-hour delay in the internal blood sugar rhythms (规律性变化).

    The discovery showed that meal times are in line with (与……一致) the body clock that controls blood sugar levels.

    This is a small study but the researchers believed the findings could help jet lag (飞行时差反应) sufferers and night-shift (夜班的) workers.

    In a study by the University of Surrey in 2013, researchers explored what happened when a person's body was changed from a normal pattern to that of a night-shift worker's.

    After people work through the night, over 97 percent of the body's rhythmic genes are disrupted (扰乱).

    These findings explain why we feel so bad following a long flight, or after working at night, according to Simon Archer, one of the study's researchers.

    “It's like living in a house. There's a clock in every room in the house and in all of those rooms those clocks are now disrupted, which of course leads to chaos (混乱) in the household,” fellow researcher Derk-Jan Dijk told the BBC.

    Changing meal times didn't affect the “master” body clock – the one controlling when we get sleepy – but it can reset the body clock that controls blood sugar levels.

    This wouldn't necessarily cure jet lag completely, but it might reduce the negative effects.

    A study published earlier this year suggested that just a weekend camping trip could be enough to reset our body clocks. And now this latest research shows regular food schedules could play a key part too.

    In Western countries people have been using the installment plan since the first half of the twentieth century. Today, a large number of families in Great Britain buy furniture, household goods and cars by installments In the U. S. A, the figure is much higher than in Great Britain, and people there spend over 10 percent of their income on the installment plan.

    The price of an article bought on installments is always higher than the price that would be paid by cash. There is a charge for interest. The buyer pays one quarter or one third of the price as a down payment when the goods are delivered to him. He then makes regular payments, weekly or monthly, until the full price is paid up. The legal ownership of the goods remains with the seller until the final payment has been made.

    Installment buying has advantages and disadvantages. It can help couples with small incomes to furnish their homes and star housekeeping. It increases the demand for goods, and in this way helps business and employment. There is, however, the danger that when business is bad, installment buying may end suddenly, making business much worse. This may result in a great increase in unemployment. If the people on the installment plan lose their jobs, they will probably not be able to make their payments. If great numbers of people are not able to pay their installment debts, there is a possibility that businessmen cannot collect their debts and will therefore lose money. If businessmen lose money or fail to make a satisfactory profit, it becomes more likely to have a depression. This is why, in some countries,the government controls the installment plan by fixing the amount of the down payment and installments to discourage people from buying more than they can pay for on the installment plan.