Elephants are the largest living animals on land. More than 500 1 kinds of elephants were found on the earth over the last 55 million years. Only 2 kinds are still alive today: the African elephant and the Asian (or Indian) elephant. These elephants can only be found in 3 places. However, the older kinds lived in cold places a long time4. An example is the mammoth (猛犸象) — the largest hairy elephant.

    The mammoth was the largest living elephant, which was about seven tons. 5 the elephants today, mammoths had black or dark brown hairs 6their bodies. All the mammoths had tusks (长牙).

    Scientists found most of the extinct (灭绝的) animals by 7 the fossils, 8 their bones and teeth that could be found. However, mammoths are quite different. During the Ice Age, mammoths died and were covered 9 in the ice. The ice kept them very well. So scientists could find the 10 body of the mammoth.

    A major development to self-driving cars may change the way we will drive in the future. Google, the leading company in self-driving technology, has changed its develop plan. It had driverless cars built by car factories, but now it will start building its own cars.

    Google has started to build some kinds of experimental electric self- driving cars that look like a Smart car or Fiat 500. There is no steering wheel(方向盘), gas pedal or brake. The only things a human passenger controls are a red "e-stop" button (按钮) for fear stops and a start button. The car's only "friendly" face is designed to make it help people accept self-driving technology.

Google workers took part in a long experiment, in which they used self-driving cars for their usual travel to work. No accident happened, but Google's heads realized that depending on a human passenger to drive in an emergency(紧急情况) wouldn't work because they may be reading, working , or sleeping. Now the self-driving car drives by itself if the driver takes his hands off the wheel for over ten seconds.

Google recently announced that its cars had covered 700,000 miles of public roads, and they were now running in busy city streets. People who love self-driving cars say this will improve transport by making roads safer, cutting down accident, and making less pollution.

    Of course, there's no need to look for parking at a crowded shopping mall. Instead, users could let their self-driving cars drop them off to park itself. A mother who took a test ride said that having the car would allow her more time to catch up with her son. The cars could also allow people who might not be able to drive to enjoy the hand-free driving. And drunk driving? Not a problem. It is very likely that by 2020, driverless cars will be common. Do you believe so?

    The solar powered bicycle—"Cycle Sol"(太阳能自行车)

A person riding a bicycle uses little energy to make the bicycle move, and there is no pollution at all when you are1. But in some countries most people don't go to work by bicycle because they wouldn't like to spend more time and feel2.

    These3a solar powered bicycle has been invented in England. Persons who ride it may not feel tired, and it's good4the environment.

    The solar-powered bicycle5an electric bike(电动车) but the motor(发动机) runs on a solar energy battery.

    The bright yellow "Cycle Sol" looks like a normal cycle but has a canopy lined with solar cells overhead (可以接受太阳能的天棚装置).

    The bicycle can be left in the daylight to charge(充电), even when the sky is6. You can leave it outside the office during the day to ride to7. These days solar cells are pretty good at8light, so it should still work when the sky is cloudy. 9night, the small battery can be charged using the main electricity in just a few hours. To save energy, when you're peddling up a steep hill, you can turn off the motor. And if10rains, the cell will keep you dry.

    There have been many great inventions that change the way we live. The first great 1was one that is still very important today-the wheel. This made it easy for man 2heavy things and to travel long distances. For hundreds of years after that, there were 3inventions that had as much effect as the wheel. Then in the early 1800's the world started to change 4. There was little unknown land left in the world. People did not have to explore much anymore. In the second half of the 19th century many great inventions were made.      5them were the camera, the electric light and the radio. These have all become a big part of our life today.

    The first part of the 20th century saw more great inventions. The helicopter in 1909. Movies 6sound in 1926. The computer in 1928. And jet planes in 1930. This was also a time when a new 7was first made. Nylon came out in 1935. It changed the kind of clothes people wear. Of course new inventions continued to be made. Man began looking 8 ways to go into space. Russia made the first step. Then the United States took another. Since then other countries，including China and Japan,9their steps into space. In 1969 man took his biggest step away from earth. 10first walked on the moon. This was certainly just a beginning. New inventions will someday allow us to do things we have never yet dreamed of.