In many high schools, there are strict rules about using mobile phones. If your phone rings in class, for example, the teacher will be very angry.

    Every mobile phone has a ringtone (铃声). It tells you that someone is calling you. Now, there is a ringtone called “mosquitotone (蚊子铃声)”.

    Mosquitotone has a special sound. Only children and teenagers can hear it. As we get older, we are unable to hear some sounds with high frequencies (频率). As a result, a child or teenager can hear the mosquitotone ringtone, but someone of 20 or older can't.

    But sometimes, people over 20 can hear the ringtone. One British student's phone uses mosquitotone. In class, the student's phone rang. The 22-year-old teacher looked at the student and became unhappy. “I heard that. You know the rule：no mobile phone in class. ”

    Not all the students are interested in mosquitotone. Jerry Jones, a high school student of 17, says, “Using mosquitotone too often is bad for our hearing. I may use it for pleasure, but not in class. It's unfair(不公平的) to the teachers！”

    What do parents think of mosquitotone？“I think it is perfect for places like movie theaters,” says Connie Neeson, 44. “Think about it. You're watching a film and someone's mobile phone rings. Mosquitotone is good because many people don't hear it. However, it also has a bad influence（影响） on their study if students use it in class. ”

    In nature，you may see many insects and animals of different colors．Have you ever wondered why?

Locusts(蝗虫)are super delicious food for birds，but it is not always an easy job for birds to catch them．It is neither because locusts are good jumpers or runners nor because they are smarter than their enemies．The reason is that the colors of locusts change with the colors of crops(农作物)．When crops are young，locusts look green．But when autumn comes，locusts change to the yellow and brown color as crops do．

    Brown bears，tigers and other animals move quietly through forests．They can't be seen easily by their enemies．This is because they have colors similar to the trees．For the same reason．polar bears that live on a land of snow and ice are white．Butterflies and bees living among the flowers are colorful like flowers．Soil insects are mostly dark—colored and they live under the soil in a dark and wet environment．However，insects with colors different from plants can easily be found and eaten by others．So in order to survive ， they have to hide themselves in the daytime and appear only at night．

    Have you ever noticed some even stranger acts? The ink fish in the sea can send out some very black ink when it faces danger．As the ink spreads over．its enemies will not find themselves suddenly in a dark world．At the same time the ink fish immediately swims away．That is how it keeps itself save though it is not strong at all．

    We choose food to eat every day．We might know some of the reasons for the choices，but food scientist Dr．

    Brian Wansink has found that we are unaware of 90% of our food decision．Here are some"big ideas"in his research on the hidden power that drives our eating．

    Food for thought

    In one of the studies，Dr．Wansink made volunteers eat chocolate yogurt in a dark room．He told them the yogurt was with a taste of strawberry even though they were all eating chocolate．Finally，65% of volunteers described the yogurt as having a"nice strawberry flavor!"

    The research shows that our imagination has an effect on our taste．If you expect a food to taste good，it will．So take a moment before you eat your unpleasant healthy food to remind yourself that you are eating delicious fish and chips．

    Our eyes eat first

    How your food looks is just as important as how it tastes．Dr．Wansink gave cakes to three groups of people．The cakes were exactly the same but served in different ways．

①Group one got the cake on a nice plate．

    ②Group two got the cake on a paper plate．

    ③Group three got the cake on a piece of paper．

    Dr．Wansink then asked the people how much they would pay for each cake．

    Dr．Wansink then asked the people how much they would pay for each cake．

    ①Group one who got the cake on a nice plate would pay $1.27．

    ②Group two who got the cake on a paper plate would pay 76 cents．

    ③Group three who got the cake on a piece of paper would pay 53 cents．

    Take some time to make your healthy food look amazing．Cut your fruit into a flower shape and put your colourful vegetables on nice plates．This works really well for your appetite （胃口）．

    Out of sight，out of stomach

    Dr．Wansink also found that when people sat at the desk full of snacks，they ate 71% more of snacks a day than those sitting near a clear table．We eat what we see．As a result，put all the unhealthy food in your fridge．

    Hide it and make it really hard to get to．The closer bad food is，the more you eat it．

New Energy in the Twenty-first Century

Energy from wind

    Wind is a kind of clean energy, and there is lots of it, but, if there's no wind, there is no wind energy.

Energy from the water

    When water from a high place to a lower place, it can make electricity（电） without pollution. However, people have to build dams（水坝） to use this energy, and building dams is very expensive.

Energy from the earth

    There is heat in the rocks under the earth. Scientists use the beat to make geothermal（地热的） energy. This kind of energy is cheap and clean, but it is only possible in a few places in the world.

Energy from the sun

    Solar panels（太阳电池板） on the roofs of house can tum energy from the sun into electricity. Solar power is clean and plentiful（丰富的）. When the weather is bad, it doesn't work.

    Last year, a special kind of glove came out. It was invented to help blind people to learn Braille, which is a special system for the blind to read by touching. Shaking motors (震动马达) are put on each finger of the glove. They can make different sounds to tell a user which letter he is touching. Recently, two British college students have invented another special glove for the blind. It can make the user feel small and quick movements. An ultrasonic sensor (超声波传感器) with a battery is put on the back of the glove. When the user wearing the glove is close to an object(物体), ultrasonic waves (超声波) from the glove are sent out (发出). As soon as they hit the object in front, the waves will return to the glove. Then the waves cause the glove to shake. And the ultrasonic sensor makes different kinds of sounds. The sounds make the user know how far he is from the object.

    In the college invention competition, the two students got first prize and won 1,540 pounds. One of the designers said, "Now the ultrasonic sensor on the glove is quite large. We're going to use the money to develop a smaller and lighter ultrasonic sensor."