The world itself is becoming much smaller by using modern traffic and modern communication. Life today is much easier than it was hundreds of years ago, but it has brought new problems. One of the biggest problems is pollution.
    To pollute means to make things unfit or unclean to use. Pollution comes in many ways. We see it, smell it, drink it and even eat it. Pollution is beginning to threaten (威胁) our health, our happiness and our life.
    Man has been polluting the earth from the time he first made fire, washed his clothes in the river and threw his waste on the ground. When land was used up or water became dirty, men moved on to another place. At first, the problem was not so serious because there was plenty of clean air, land and water. There weren't so many people then and their wants fewer. All the dirty things could be absorbed(吸收) by nature and soon covered over. But this is no longer true. The increase of pollution and the development of industry(工业) have changed that. Man is slowly poisoning(毒害)not only his environment but also himself.
    Through the use of poison, man has polluted the land, killing the animals. By putting dirty water and chemicals into rivers and lakes we have polluted our drinking water, killing the fish.
Our increasing population is part of the problem. More people, more waste.
     Where is this all to end? Are we turning the world into a big rubbish dump(堆存处)，or is there any hope that we can get rid of (摆脱，除去) the pollution? Luckily, millions of people have been warned of the danger of pollution. Large numbers of people are now working hard to bring pollution under control.
    The earth is our home. We must take care of it. This means keeping the land, air and water clean. And we must take care of the rise in pollution at the same time.

B

    Many years ago, there was a very popular sport in America. Who invented the sport more than 3,000 years ago? We don't know. But everyone thinks it was the Olmecs(奥梅克人）made it popular.

    People don't have the same rules about the game all over the world. People in different parts of the world play the game in different places at different times. If we want to bring back the sport, we need to have two teams of players standing on each end of a court. When the game begins, the two teams need to pass a ball from one side of the court to the other. The players can't touch(触) the ball with their hands and feet. But they can use their elbows(肘) and other parts of their bodies hit it. If a player does not pick up the ball in time and lets it fall to the ground, that team loses a point. But if a player makes the ball through a hoop(环),that team scores a point. The team with the most points wins the game.

    Scientists have been experimenting with four-leg robots for years. They want to use robots to carry heavy things over difficult land.

    But providing enough power for those kinds of robots has been a problem. Now, that has changed. Engineers at MIT have designed a running robot that runs on batteries. Scientists say their robots will soon be able to run like cheetahs, the fastest land animals on Earth.

    One difficulty in designing these types of robots continues to be providing power. These machines are still quite heavy and they need a lot of power to run. But the cheetah-like robot designed by engineers at MIT is light enough m run on batteries. The robot weighs just 30 kilograms. The robot needs only about 700 watts of power to run. This robot can actually jump 40cm high and it can land very safely and then it can run. The robots limbs and other parts were made in a three-dimensional or 3D printer. A strong, light-weight material called Kevlar is used to make the robot's part stronger.

    But the development of MITs robot is not without its own set of problems. The robot's limbs must support heavy force, and sometimes they break.

    Scientists say the new technologies used on this robot may be used in the making of limbs for disabled persons and other machines. Some of those machines may help save humans from performing difficult and dangerous jobs.

    You know how much your telephone has changed over the past 10 years? Your car will change even more than that in the next 10 years. One of the biggest changes is that cars will drive themselves.

    "We certainly have the technology for it now." says Andrew Poliak of automotive(机动车辆的)technology supplier QNX." We expect self-driving cars to be a mainstream thing between 2020 and 2025."

    The American company Google has been working on self-driving cars for years. These cars are already on the roads in the United States and are truly self-driving. They have to steering wheels(方向盘）or pedals(踏板). Last week, the police ordered one of Google's cars to stop for driving too slowly on a public road. The car was not breaking any law, so no one was punished.

    Another American company, Tesla, added an "Autopilot" feature to its cars last month. With the Autopilot turned on, the vehicle drives itself. The car will speed up, slow down, brake and drive by itself. You can take over driving any time by turning the steering wheel or touching a pedal. The car uses sensors to know when driveway changing is safe and whether it should speed up or slow down.

    Tesla Autopilot is made for cross-country driving. It keeps you in the driveway and helps you avoid hitting other cars. It does not work well on local roads, for it will not stop at a red light or stop sign.

    Reporter Carolyn Nicander Mohr tried the Autopilot feature of a Tesla earlier this month. She had a hard time trusting the car to do what it should do. She thought about disabling the Autopilot feature many times during her trip. She wanted to take control at every bend in the road and hit the brake when the car in front of her slowed down. Yet the car drove perfectly.

    Other companies are working on self-driving cars, too. Marcedes-Benz, Audi, BMW. Volvo and Toyota all have plans for such vehicles.

    Dinosaurs, one of the most successful groups of animals that have ever lived, evolved(进化) into many sizes and shapes. The word "dinosaur" was invented by Sir Richard Owen in 1842 to describe these "fearfully great reptiles(爬行动物) ".

    Some things to keep in mind about dinosaurs：

    ·Not everything big and dead is a dinosaur. Dinosaurs were a special group of reptiles. Although Pterosaurs(翼龙) were similar, they were not true dinosaurs.

    ·Not all dinosaurs lived at the same time. Different dinosaurs lived at different times. Although you can see Stegosaurus(剑龙) fought against Tyrannosaurus

(暴龙) in some movies like King Kong and Jurassic Park, no Stegosaurus ever saw a Tyrannosaurus. It's because Tyrannosaurus appeared on the Earth about 80 million years after Stegosaurus died out.