Many people say dolphins are very intelligent(聪颖的). They seem to be able to think, understand, and learn things quickly. But are they c like humans or more like cats or dogs? Scientists say dolphin intelligence is s to human intelligence in some ways. How?

    Like humans, every dolphin has a "name". I is a special whistle(哨声). Scientists think dolphins, like people," t"to each other about a lot of things, such as their age, their feelings, or finding food. And, like humans, dolphins use system (系统)of sounds and body language to c. But understanding their conversations is not easy for humans. No one "speaks dolphin" yet, but some scientists are trying to learn.

    Dolphins arc also social animals. They live in groups, and they often come to play games from different groups and have f, just like people. In fact, playing t is something only intelligent animals do.

    Dolphins and humans b make plans to get something they want. In the seas of southern Brazil, dolphins use an interesting way to get food. When fish are n a boat, dolphins signal (发信号) to the fishermen to put their nets in the water. And the men can catch a lot of fish. What is the advantage for the dolphins? Why do they h the men? The dolphins can get some of the fish.

—No, you ______. You can answer it in Chinese.

    Big ocean fish have almost been endangered since the start of business fishing in the 1950s. The scientists found that the number of large fish has dropped by 90 percent in the past fifty years. The study took ten years. The researchers collected records from fishing businesses and governments around the world. The magazine Nature published (发表) the findings.

    The scientists say the common way called long line(多钩长线) fishing is especially harmful to large fish. This way includes many fishing lines that are connected (连接) to one boat. If these lines are joined together, they can reach one hundred kilometers. They hold thousands of sharp metal hooks to catch fish. Long line fishing is especially common in the Japanese fishing industry. Records showed that Japanese boats used to catch about ten fish for every one hundred hooks. The study says long line fishing boats now might catch one fish per hundred hooks.

    The scientists say business fishing can destroy groups of fish much faster than in the past. The study suggests that large fish can disappear almost completely from new fishing areas within ten to fifteen years. Ocean life systems could be destroyed.

    It's not the only worry that the number of large fish is becoming smaller and smaller. What's worse, they are smaller in size than their ancestors (祖先).

    There are some easy things you can do to protect the environment and the earth. Choose ideas from the list or come up with a few of your own.

    •Plant flowers, grass or trees.

    •Whenever you visit a park or beach, take away what you bring there—keep rubbish in a bag until you can put it in a dustbin.

    •Turn off the lights and TV sets when you leave the room. This can save a lot of electricity.

    •Turn off the tap when you brush your teeth. You can save some water by not letting it run. Also, use a glass cup instead of a paper cup because this saves paper.

    •Keep the doors and windows closed in winter to keep warm air in.

    •Give your old books and magazines to a library instead of throwing them away.

    •Give your old clothes to poor children you know instead of throwing them away.

    •Use both sides of paper.

    •Stop pouring dirty water into the rivers or lakes nearby.

    •Encourage all your friends to do the same things you do to help protect the earth. You don't have to wait until Earth Day to do these things. Make every day Earth Day. If everyone makes a contribution to protecting the environment, the world will become much more beautiful.