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

    Locusts 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(庄稼). 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(土壤)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 find themselves suddenly in a dark world. At the same time the ink fish immediately swims away. That is how it keeps itself safe though it is not strong at all.

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    Google and Toyota have worked together to create a new smart car. It can run on the road without a driver. It drives itself. The self-driving car hasn't been on sale to the public, so we don't know how much it costs. Another thing most people want to know is whether it will be safe enough to run on the road.

The self-driving car uses electricity (电) as its power, and it can't drive very quickly—the top speed would be 25 miles per hour. It is actually controlled by a computer system on the car. The system keeps on collecting information by some video cameras inside the car and a LIDAR sensor(激光达传器) on top of it. A computer processes the information and decides what to do. "The self'-driving car has only buttons (按钮) for go and stop, so it's very easy to use," an engineer of Google says. "And what's more, it will make car accidents fewer and make the world a safer place." The self-driving car has driven hundreds of thousands of miles in California, and it has only gotten into two accidents by human mistake.

    According to CNN, self-driving cars will also help to reduce the number of cars in big cities. "Self'-driving cars would be able to send you to the workplace and then pick up another person instead of stopping in a parking lot."

    How do you keep cool during summer? Air conditioners or electric fans are good 1 in modern society. But 2 that, people could only use fans.

    Over 3,000 years ago, fans began to 3 They were made of feathers (羽毛), bamboo or silk. They came in different 4 , including round and square.

    Later, with the invention of paper, folding(可折叠) paper fans became popular5 the Song Dynasty.  There are usually beautiful 6on fans. Some are landscapes (风景). Others are flowers and animals. Moreover, many great people including Su Dongpo, a poet of the Song Dynasty, and Tang Yin, a scholar (学者) and painter of the Ming Dynasty, once painted their masterpieces(杰作) on fans. This made fans not only 7 tools in daily life but also great artworks.

    So, with its value of beauty, people take fans as a 8 of status(地位). That's why in old China, emperors and scholars often held fans.

    Today, fans are also great collectors' items(藏品) and gifts. On the opening ceremony of the 2008 Beijing Olympic Games, folding fans were9 to leaders and officials (官员) of other countries. While they were 10 fans to get cool, they were also experiencing Chinese culture.

    They say music is universal, and it seems to be true since wherever we go, we see people listening, playing or dancing to it. We tend to think that music is larger than our cultural differences and shows the deeper connections between us.

    But according to a recent study published in the Current Biology, music doesn't speak to everyone. There is a condition, the researchers argue, called "musical anhedonia". They say that those who have this condition may have few abilities to experience pleasure from music.

    For the study, 30 people listened to the same, mostly classical music pieces. They were then asked to complete a questionnaire on how they felt about the music. At the same time, the researchers measured their heart rate and skin reaction, which are considered physiological measures of feelings.

    According to the researchers, most of the people in the study got pleasure from the music. They had a quicker heartbeat and sweatedmore. However, a small number of them had very little and even no pleasant feeling while they were listening to the music. These people had none or very few of the physical signs which the others in the study experienced.

    The researchers say that this means people have different abilities to enjoy music and that "there are people who specifically can't enjoy music at all"

    To study the condition more deeply, another group of scientists, at Columbia University, US, researched brain activities. They found that the key is the blood flow to the reward system in the brain. People who got less pleasure from music had comparatively lower blood flow to areas involved in the reward system of the brain when they were listening to music.

    The lower blood flow makes it more likely that the brain's "reward system" will be inactive. And it will produce less of the "pleasure chemical" dopamine. As a result, people get less pleasure from music.

    If the research is correct, according to National Public Radio, there are simply people who just don't get music. They may get pleasure from many things, but a good tune isn't one of them.

    Man is a land animal, but he is also closely tied to the sea. Throughout history the sea has served the needs of man. The sea has provided man with food and a convenient way to travel to many parts of the world. Today, nearly two—thirds of the world's population live within 80 kilometers of the sea coast.

    In the modern technological world, the sea offers many resources to help mankind survive (=continue to live). Resources on land are beginning to be used up. The sea, however, still can be hoped to supply many of man's needs.

    The list of riches of the sea yet to be developed by man's technology is impressive. Oil and gas explorations have been carried out for nearly 30 years. Valuable amounts of minerals exist on the ocean floor ready to be mined (开采).

    Fish farming promises to be a good way to produce large quantities of food. The culture of fish and shellfish (贝类动物) is an ancient skill practised in the past mainly by Oriental people.

    Besides oil and gas, the sea may offer new sources of energy. Experts believe that the warm temperature of the ocean can be used in a way similar to the steam in a steamship. Ocean currents (水流) and waves offer possible use as a source of energy.

    Technology is enabling man to explor ever more deeply under the sea. The development of strong, new materials has made this possible.

    The technology to harvest the sea continues to improve. Experts believe that by the year 2000 the problems that prevent us from exploiting fully the food, minerals, and energy sources of the sea will be largely solved.

    If there is no rain, there will be no water to drink. We can only live for about three days without water. If there is no rain, we'll have no water to brush our teeth. We will have no water to take a shower. We will have no water to wash dishes or our clothes.

    Plants and animals need water to grow. If there is no rain, they will die. We will not have any rice, any vegetables or any meat. If there is no rain, we will have nothing to eat. We can only live for about one or two weeks without food.

    If there is no rain, there will be no water in the streams or rivers. Fish will have nowhere to live. They will die. We will have nowhere to swim.

    If there is no rain, the cooks in the restaurants will have no water to cook food.

    If there is no rain, firemen will have no water to put out fires.