B

    People often think of the North Pole(北极) and the South Pole as similar frozen(冰冻的) wastelands. They are both places with very cold temperatures and few people live there. However, the North and South Poles are not much alike as people may imagine.

    The North Pole has no land, only thick ice. Temperatures seldom go above 32°F, at which water turns into ice. Most of the time, it stays below zero. In winter temperatures are usually as low as -30°F.

    Although conditions were very poor, people tried for many centuries to reach the North Pole. About 100 years ago, two men, Robert Peary and Mathew Henson, were able to get to this environment full of troubles and difficulties. They reached the North Pole on March 8th, 1909. It was really a hard trip for them.

    There are few things more dangerous than crossing the Arctic(北极圈) on foot. People who stayed there may face many problems: very cold temperatures, sudden storms, and even hunger. Most of the area is uninhabited. Few people can live in such a difficult place.

    People might think that with such low temperatures for most of the year, the ice would be thick and hard. However, this is not true in the Arctic. The movement of the ocean water under the ice may often cause many different changes on the surface. Sometimes the ice breaks into two opening lanes of water(水道) called “leads”. Anyone who falls into a lead can be frozen to death in a few minutes.

B

    You probably know many of the things that you can do with the hundreds of different muscles（肌肉） in your body. But have you ever thought about how the muscles in an animal's body are different from yours? An animal's muscles are made to do the things that are the most important for its life.

    Lions are hunters. They depend on their ability to catch other animals. Lions must be fast in order to catch their prey(猎物). The powerful muscles in their back legs allow them to run at speeds of more than 30 miles per hour. They can also jump a distance of more than 35 feet. The strong muscles in their front legs help them catch their prey.

    Snakes also use their muscles for hunting prey and for movement, but their muscles work in very different ways than lion's do. Because snakes do not have any legs, they use their muscles to push against the ground or other objects to move themselves forward. Their muscles also allow them to eat things that seem much too large. For example, a snake may eat an egg that is larger than the width of its body. How does this happen? The snake's strong neck muscles work together to push the egg down the mouth.

    The elephant's long nose has a lot of muscles. Scientist believe that the nose alone has more than 100, 000 muscles! This is because the elephant uses its nose much in the same way that people use their hands and fingers. Even though the nose is large, it can perform surprisingly tasks. For example, an elephant can pick up a tree by its roots or even to lift a baby elephant.

    The great muscles of these animals seem pretty unbelievable. But the muscles in your body work exactly the way you need them to. After all, it might be fun to be able to jump a distance of 30 feet, but as a human being, there is just not much need for it.

    In recent history, there have been some amazing inventions which have changed our lives. The plane has made international travel faster and easier. The Internet has brought people closer. And you must know the names of some famous inventors like Henry Ford or Steve Jobs. But there are many everyday objects which you probably don't notice and you don't know who invented them. Take for example Nils Bohlin who invented the modem-day car seat belt (安全带).

    Before 1959, only two-point seat belts were available, and the only people who often wore them were race car drivers. The two-point seat belt couldn't protect passengers from internal injuries (内伤) during serious car accidents.

    In 1958, Bohlin joined Volvo Car Corporation as a safety engineer. Then he came up with the three-point seat belt to keep passengers from flying out of their cars during collisions. The three-point seat belt used one strap (带子) across the chest (胸部) and another across the legs and then the two joined at me same place.

    Amazingly, this was a very simple idea which no one had tried before. The three-point seat belt was introduced on Volvo cars in 1959. For more people's safety, Volvo made the new seat belt design available to other car makers for free. Since then, engineers have worked to improve the three-point seat belt, but the basic design remains Bohlin's.

    At the time of Bohlin's death in September 2002, Volvo announced that the seat belt had saved more than one million lives since it was introduced.

    Light and shadow（影子）are friends. They usually go together. We receive light every day. At the same time, we produce shadow.

    Light cannot shine through you. Your body stops it from passing. There is a dark spot on the ground next to you. The light cannot reach the dark spot. This is your shadow.

    At noon the Sun shines over your head. Your body stops very little light from reaching the ground.

    We love light, especially sunlight. Without sunlight, life on the Earth is impossible. Most of us like to stand in the shadow of a tree in summer. But some people are afraid of their own shadow at night. They do not want to walk in a dark street. They do not want to see the shadow either. But still light and shadow usually go together.

    We all know that many women like to wear dresses. They enjoy many kinds of colourful and popular dresses. But have you ever heard of a 4D dress?

    Jessica Rosenkrantz in the USA used 3D printing technology to make a very special and new dress. It will help with the problems of different styles of women's dresses.

    The dress maker called the special dress a"4D dress" ". It is like the fabric(织物). It can turn into different kinds of shapes.

    The company, in Massachusetts, the USA, also made a smartphone and an app(应用). They can help women to control their dresses. If women use the phone and the app, they can change the colour, the style and many other things of the dresses. Isn't it very interesting?

    When she talked about her work, Jessica said, "There will be many more changeable dresses for women in the future. I am interested in making them too, I can't wait to make different kinds of new dresses for women."