C

    Paul is a photographer(摄影师). He went to the Arctic to take pictures for NationalGeographic(《国家地理》). Finally, he saw a big and white polar bear swimming to him in the icy water.

    Paul lay down the ice to get a better photo, but the polar bear jumped out of the water and tried to attack him! Luckily for Paul, the ice cracked(破裂), or broke and the bear fell back into the water. The polar bear wasn't so lucky. It couldn't get a meal and had to swim farther away to find food.

    To understand the polar bear's problem, you need to know two things about the Arctic. First, the Arctic is mostly ocean(海洋). Second, ice covers(覆盖) a lot of the Arctic Ocean. In winter, the ice is thick, but in summer, the ice becomes thinner and breaks into pieces. Sea ice is the key to survival for Arctic animals. However, because of global warming, Arctic temperatures are rising and polar ice is melting(融化).

    Polar bears need ice  to hunt(捕捉) seals, their favourite meal. They stand on the ice and wait for the seals to come up for air. As Arctic ice melts, polar bears have to swim farther to find ice floes, or large pieces of floating ice. Sometimes, bears have to swim more than 200 km to find an ice floe. Some bears cannot swim that far and sadly they drown(淹死).

    On his last trip, Paul saw three dead bodies of polar bears. Before global warming threatened(威胁) Arctic ice, a dead bear was a rare sight. Paul is sad to see the dead bodies. Wildlife experts(专家) think global warming will have a terrible effect(影响) on polar bears. In the future, polar ice will continue to shrink and endanger the bears. Some scientists believe 65 percent of the world's polar bears will disappear(消失) by 2050. In other words, polar bears are in great danger.

    The Internet joins millions of computers all over the world,and today it is used by people all over the world.It was invented in the 1960s in the USA.The American government needed a network of computers for its army.Then in the 1970s scientists and business people also wanted to use the Internet to send and receive messages.For some years,they weren't allowed to use the US network,and when they were allowed to,the messages were in very simple text without photos.

    The World Wide Web was invented by a British scientist named Tim Berners-Lee in 1989.He wanted to send documents to other scientists,so he developed the World Wide Web.This allowed him to send and receive scientific documents with text,drawings and photos(also called multimedia documents).In the 1990s,more and more people began to use the Internet and the World Wide Web.

    So what's the difference between the Internet and the World Wide Web?The Internet is the hardware.It allows us to communicate with other people.The World Wide Web is the software.It allows us to create, see and read multimedia documents.

    The Web is made up of millions of documents called Web pages.These pages are held in computers all over the world.Many people have a favorite website with a number of Web pages on the same subject.

    The email is a way of using your computer to send and receive messages.It's cheaper and quicker to use emails than send normal mails.New users call the normal mail “snail mail” because it's too slow.It took 50 years for 100 million people to listen to the radio.It took 15 years for 100 million people to watch television.By the year 2000, it had taken only about three years for 100 million people to use the Internet.What will happen next on the Internet?

    The days of having to carry a phone charger(充电器) everywhere could soon be over. Researchers from America have made great progress in getting energy from human motion(运动). They say smartphones could get enough power just by the motion of fingers on the screen.

    The low-cost device(装置) has already been tested in an American university. Scientists successfully showed an LED touch screen, a total of 20 LED lights and a keyboard, all with a simple touching or pressing motion and without the help of a battery.

    "What I predicted is the possibility of not having to charge your smartphone for a whole week, for example, because that energy will be produced by your motion," said one of the researchers.

    The completed device is as thin as a piece of paper. Electrical energy is created when you press it. The device used to power the LED lights is the size of a hand while the device used to power the touch screen is as small as a finger.

    The device will become more powerful when folded. Each time you fold it, the energy you create will be doubled. You can start with a large device, but when you fold it once, and again, and again. It's now much smaller, but it has more energy. It may be small enough to put in a specially made heel(脚后跟) of your shoe so it can create power each time your heel knocks the ground. The researchers are also developing technology that would send the power produced from the heel strike to an earphone.

Paul is my good friend. This is his 1 . It's small, but it's always 2 . His bed is in the middle of the room. And a yellow quilt is 3 the bed. Paul loves yellow. Look! The bookcase is 4 , too. In it, you can see some books. A black computer is on the table, 5 it's not Paul's. It's his father's. 6 is that next to the computer? It's a photo of his family. There are 7 people in it, his parents, his sister and him. Where is 8 phone? Oh, he lost it. Do you 9 it? If(如果) you do, pleasee-mai lhim10 PAUL3456@126.com.Thanksalot.

Knowing the City by Walking

From July 2022 to July 2023, city walkers in China together covered over 320,000 kilometers. That's like circling Earth 8 times.