阅读理解。

Hover Camera(无人相机)

    Wang Mengqiu, the inventor of Hover Camera, was born in Hangzhou in 1982. He once studied at Stanford University in the United States. He became famous overnight(一夜成名) because of the invention.

    Forget selfie sticks(自拍杆)! Compared to other cameras, Hover Camera has many advantages.

    *It can fly and stay in mid-air, track your face and even follow you to make sure it gets the perfect picture.

    *It can be controlled by using a smartphone(智能手机).

    *It records movements with a 13MP camera and takes 4K video.

    *It is the best choice for weddings, sports games and holidays.

    Mr. Wang also said: “The main design consideration is easy and safe to take for the users. It's very light and small. It can be folded(折叠) in two, so it can be easily put into a bag. When the power is low, it can land on the ground safely on its own.”

    It's reported that the company has raised $ 25 million to produce it. As it is still being tested(测试), Hover Camera can be bought later this year.

The price has not yet been decided. But a spokesman says the company hopes to sell it for less than $ 600.

    Winter is very cold in many countries. It's easy for you and me to keep warm. If we are cold, we can just buy a warm coat or use a heater and we will feel better. But what about animals? How do they keep warm in winter?

    Some animals migrate(迁移). This means they travel to places where the weather is warmer. Many birds leave before the winter starts. They fly in groups. If they fly together, the trip will be safer. They like to migrate to the same places every year. Do you know how they can find the same places? Scientists say that birds use the sun, moon and stars to help them. Other animals like moose (麋鹿) also migrate. Fish and whales swim to warmer water.

    Some animals don't have leave their homes. They hibernate in winter. They fall into a very deep sleep. The animals' temperature drops and their breathing slows down. Before the winter, these animals must eat too much food that they get very fat. If they don't eat enough, they may die when they are hibernating.

    Every school day, we use schoolbags to carry all of our things to school. They are a big part of our lives. But have you ever thought about the history of the schoolbag?

    In the Han Dynasty (汉朝), students in old-style private schools used bamboo boxes to carry books to school. People consider the bamboo boxes to be the earliest schoolbags. They were usually two or three layers (层) in the box. Kids put different things like books, brushes, ink stones (砚) and paper in the boxes.

    Hundreds of years later, people developed a new kind of schoolbag called the budai, or the "hip-pocket". The budai was lighter than the bamboo box. With the founding (成立) of the People's Republic of China, military rucksacks (军用帆布包) became popular. Many people carried them when they were in school. Ask your grandparents or parents about these bags. Maybe they can tell you about their experiences of carrying them when they were in school.

    A new style of schoolbags has appeared in recent years. Many of them have colorful and fashionable designs (时尚的设计) on them, such as pictures of cartoons or pop stars. And they are more comfortable to use. Some students pull wheeled bags filled with heavy textbooks and others carry backpacks.

    Schoolbags are still changing. Can you imagine what future schoolbags will be like?

    How do you deal with plastic bags from the supermarket? Throw them away or recycle them? How about eating them?

    The bags are not harmful to the environment. Humans and animals can safely eat them. Indian company EnviGreen has made a bag with natural materials. It looks and feels just like plastic, but can be broken down(分解) easily.

    Ashwath Hedge who set up the EnviGreen company spent four years doing experiments (实验) with 12 natural materials. They include potatoes, corn, vegetable oil and bananas. He made the materials into liquid(液体) and used the liquid to make the bag.

    Although the EnviGreen bag is more expensive than a common plastic bag, it has many advantages. According to The Wall Street Journal, it takes 1,000 years for common plastic bags to break down. But an EnviGreen bag can naturally break down in less than 180 days. It also breaks down in less than a day in water, and in less than a minute in boiling water. Hedge was happy to show it in his interview, and he put an EnviGreen bag in water and ate it with a smile.

    There are more than 15,000 tons of plastic waste in India every day. But only 9,000 tons are processed. In China, 3 billion plastic bags are used

    Every day. Maybe the EnviGreen bag could be a solution to the world problem of plastic pollution,

    A black hole is a place in outer space with very strong gravity. Gravity is a great force(力量) that shapes the universe. On Earth, gravity makes apples fall from trees. It keeps your feet planted on the ground. The gravity in a black hole is much stronger. It is so strong that nothing around it can get away from it, not even light.

    Black holes are invisible. We can't actually see them because they don't throw back light. But scientists can find them with space telescopes(望远镜)and special tools. The strong gravity makes nearby stars move in a certain way. By studying how the stars move, scientists can find out if they are flying around a black hole. Strange things happen around black holes. This makes black holes a popular subject of science fiction(科幻)stories, although they are very real.

    A black hole forms when a star dies. The star falls in on itself and turns into a very small point. Because of its small size and huge mass(质量), the gravity will be so strong that it will pull light in and become a black hole. Black holes can grow huge as they continue to pull other things in and "eat" them. Many scientists believe that there are super-massive black holes at the center of galaxies, including the Milky Way.

    The idea of the black hole was first suggested by two different scientists in the 18th century: John Michelle and Pierre-Simon Laplace. In 1967, a physicist named John Archibald Wheeler came up with the name “black hole". Studying black holes can tell us many things about our galaxy and help scientists answer questions about the universe.

    Different weather makes people feel different. It influences health, intelligence(智力) and feelings.

    In August, is very hot and wet in the southern part of the United States, People there have heart trouble and other kinds of health problems during this month. In the Northeast and the Middle West, it is very hot at some times and very cold at other times. People in these states have more heart trouble after the weather changes in February or March.

    The weather can also influence intelligence. For example, in a scientific report, IQ (智商) of a group of students was very high when a very strong wind came, but after the strong wind, their IQ was 10% below. The wind can help people have more intelligence. Very hot weather, on the other hand, can make it lower. Students in many schools of the United States often get worse on exams in the hot months of the year (July and August).

    Weather also has a strong influence on people's feelings. Winter may be a bad time for thin people. They usually feel cold during these months. They might feel unhappy during cold weather. But fat people may have a hard time in hot summer. At about 18℃, people become stronger.

    Low air pressure may make people forgetful. People leave more bags on buses and in shops on low-pressure days. There is a "good weather" for health. People feel best at a temperature of about 18℃.

    Are you feeling sad, tired, forgetful, or unhappy may be the weather's problem today?