Weather has a strong effect(影响) on people. It influences health, intelligence (智力) and feelings. In August, it is very hot and wet in the southern part of the United States. People there easily have heart trouble and other kinds of health problems during this month. In the Northeast and the Middle West, it is hot at some times and very cold at other times. People in those states will have heart trouble after the weather changes in February or March.
      The weather can also influence intelligence. For example, in a 1983 study by scientists, the IQ scores of some college students were very high during storm, but after the storm, their scores were low. Storms can increase intelligence. Very hot weather, on the other hand, can decrease(减少) it. Students in many schools of the United States often do badly in exams in the hot months of the year(July and August).
      Weather also has a strong effect on people's feeling. Winter may be a bad time for thin people. They usually feel cold during these months. They might feel depressed during cold weather. In hot summer weather, on the other hand, fat people may feel unhappy. At about 65F, people become stronger.
      Low air pressure(气压) makes people feel free, but it also increases forgetful- ness. People leave more bags and umbrellas on buses and in stores on low pressure days. There is a“perfect weather”for work and health. People feel best at a tempera- ture of about 64F with 65 percent humidity(湿度).
      Are you feeling sick, sad, tired, forgetful, or very intelligent today? The weather may be the reason.

A

    Air pollution is one of the most common types of pollution in the world nowadays. It is quite serious in many places, especially in big cities. It can do great harm to our environment such as making the earth warmer, causing acid rain or destroying the ozone layer. As for human beings, air pollution causes all kinds of breathing problems.

    There are several reasons for air pollution. Firstly, many cities have a lot of factories and there we need to make food, clothing and other things. Every year these factories pour millions of tons of smog into air. Secondly, power factories can also give out harmful air. For example, in 1986 there was a bad accident at a nuclear power station in Russia. A cloud of radiation crossed the whole Europe. It is said that 125,000 people died in Russia as a result of illnesses caused by this accident. Thirdly, there are more cars in cities now. Once they are out in the streets, they will take in fresh air and give out dirty gas. Besides, smoking cigarettes also makes air pollution worse as will as damaging(损害) our health.  

    It is park at the bottom of the ocean. It's cold down there too. There's no air to breathe. The water pressure is high. There may be fishes that could hurt you. The deep sea can be an unpleasant place. But people are still fascinated by it, not just because of the amazing scenery. The seafloor might hold the secret to the beginning of life on Earth.

    Oceans cover more than two-thirds of our planet. Yet, we have explored just a small part of the underwater world. A new project is there to explore the ocean deeper. A new US machine can carry people down to as deep as 6,500 metres. It will take the place of an older machine called Alvin. The old one has been in use for 40 years, but it can only go down to 4,500 metres. Alvin played a key role in many important tasks. Alvin helped biologists collect worms, chemists gather rocks, and oceanographers (海洋学家) map the seafloor and take water sample (样本).

    But now it's about time for a new one. The new machine will be like Alvin. It'll also be about 27 feet long, about the size of a small school bus. The seating area inside will be small, about two metres wide. Like Alvin, it'll carry a pilot and two passengers. It will be able to move like Alvin does. It'll give passengers more chances to enjoy the view. Alvin has only three windows. The new one will have five. It will travel more than a mile an hour faster than Alvin. Getting to the bottom faster and moving around more quickly will allow researchers to make the most of their time underwater.

    What is the most stressful (有压力的) thing in school? It is probably exams. Exams can put us under a lot of stress. But some students do better under stress, while others do not. So, why do some students behave better under stress?

    It all comes down to dopamine (多巴胺). Dopamine is a chemical in our body that sends signals in the brain. It has many important roles: influencing memory, attention and how we learn.

    Our brains work best when there is a balance (平衡) of dopamine—not too much or too little. Our brains control dopamine in two ways. It either takes out dopamine quickly, or bit by bit. Exam success can be connected to how fast dopamine goes back to a balance, according to new research from the University of Missouri, reported Yahoo.

    What happens when we take an exam? If you become stressed, your brain will start to overload on dopamine. It is like a cup overflowing with water. The quicker you are able to go back to a balance of dopamine, the quicker you can focus, helping you do better on a test.

    Scientists found that, during a test, people who slowly got back to a balance of dopamine scored 8 percent lower. That's the difference between a good mark and a bad mark.

    But don't fear, there is good news for every student. The study also found that the more practice you get, the less stressed you will be. So, it turns out that     .

    Humans can go to the hospital when they're ill. But as for animals, what should they do？To stay healthy, animals have their own ways to heal(治愈)themselves. Now let's get to know their special skills.

    Skill One

    Have you ever seen your dog or cat lick(舔)its wounds？Why do they do it？It probably feels good, but it's good medicine. Licking cleans a wound, and saliva(唾液)has chemicals that kill germs(细菌).

    Skill Two

    To avoid diseases, many animals have good living habits. They hate to be dirty. Most animals separate their pooping(排便)areas from their eating areas. Horses poop far away from the grass they eat. Rabbits put their poop in special pooping areas.

    Skill Three

    Have you ever heard of the expression "starve a fever(发烧时宜饿)"？Many animals stop eating when they're ill. When a sick animal stops eating, it can stop germs from getting necessary things.

    Skill Four

    Another way that animals heal themselves is to raise their body temperature. High temperature can kill germs. Warm—blooded animals(like us)get fevers to fight with germs.

    Cold—blooded animals(like snakes)look for pieces of wood or rocks heated by the sun.

    Fish move to warmer waters.