1 . The Silk Road is the name of different roads that long ago connected Europe, Africa and Asia. People reached these different places along these roads. Scientists believe people began to travel the Silk Road about 3000 years ago. By the time the Chinese silk trade became important in the world, the Silk Road covered almost 6500 kilometers. It spread from Rome to China, which is from the West to the Far East.

Traders travelling along the Silk Road carried silk, of course. They also carried and traded spices (香料), cloth, valuable stones and gold.

There is a famous old story along the old road. It is said that Roman soldiers travelled through central Asia. They started to live somewhere near the ancient Chinese village of Liqian. Sortie of these Romans married local Chinese women and the story of blue-eyed villages of China was started.

During its busiest period, the Silk Road allowed people from many different cultures and countries to meet each other and mix. The Silk Road allowed the sharing of valuable goods and new ideas. These included people and trading goods from the Mediterranean, Persian, Magyar, Armenian, Bactrian, Indian and Chinese areas. All these peoples travelled the Silk Road, and they shared goods, stories, languages, and cultures.

In modern times, the old Silk Road routes (路线) are still used, but now they are crossed by trains instead of camels and horses. There is even a Silk Route Museum in Jiuquan in China. It has over 35,000, objects from all along the Silk Road. In this way, China protects the history of many countries and peoples.

2 . In habitats across the planet, animals periodically drop everything to walk, fly or swim to a new place. Some animals such as whales and geese learn migration paths by following their parents. Others, including small songbirds, gain the distance and direction of their migration within their genetic code. And some animals use a combination of genetics and culture to guide their migration.

Another group of migrators does not quite fit either model, and researchers have only recently started to figure out how they find their way. The Cory’s shearwater is an oceangoing seabird that migrates over the Atlantic every year. The young do not migrate with their parents, so culture cannot explain their journeys. And the exact paths vary wildly from individual to individual, making genetics equally unlikely.

Cory’s shearwaters are long-lived, rarely producing young successfully before age nine. This leaves an opening for learning and practice to develop their migration patterns. Researchers call this the “exploration-refinement”, and until now it has been hypothetical (假设的) because of difficulties in tracking migratory animals’ movements.

But a team of researchers has done that by attaching small geolocators to more than 150 of the birds aged four to nine. They found that younger birds traveled longer distances, for longer periods, and had more diverse paths than older birds. “We finally have evidence of the ‘exploration-refinement’ for migratory birds,” says Letizia Campioni, who led the study. Younger Cory’s shearwaters are able to fly just as fast as the adults——but they do not, suggesting that the young do more exploring, which gradually fades as they mature and settle into a preferred course.

“Although it may seem less efficient than other strategies, exploration refinement could be beneficial to birds and other organisms in a rapidly changing world due to unpredictable man-made changes,” says Barbara Frei. “It might be safer to repeat a behavior that was recently successful than to rely on patterns that were perfected long ago but might no longer be safe.”

3 . On Saturday 24 August 1918, it was raining cats and dogs and thundering over a city called Sunderland on the northeast coast of England. The storm lasted for only about ten minutes. People were surprised to see that it was not just rainwater falling from the sky. There were fish falling down, too! People came out to find out what was happening. They could not believe their own eyes. There were thousands of fish—sand eels (沙鳗)—lying on the ground. They were about seven centimeters long, and all were frozen solid (冻成硬块).

Sand eels swim together in large groups, often in sandy water, and are often found in large numbers in the North Sea, which reaches out to the east of Sunderland. How was it possible for these sand eels to fall from the sky and land on Sunderland?

Scientists believed the heavy thunderstorm that afternoon may have caused a waterspout (水龙卷). Waterspouts can be formed when strong winds move quickly in a circle over water. They are so powerful that anything less than one meter in length can be taken into them and forced into the clouds. The clouds carry whatever has been taken into them for long distances —sometimes over 150 kilometers. It’s very cold up there and everything soon freezes solid.

For hundreds of years there have been reports of small animals being taken into the sky through waterspouts. In 2009, dead tadpoles rained down on the city of Nanao in Japan. In 2012, fifty kilos of prawns fell from the sky over Sri Lanka. In 2017, fish fell on the coastal city of Tampico in Mexico.

It must be a very strange experience to see fish raining down on you. It would probably hurt if one fell on your head! With climate (气候) change and many reports of terrible storms, will the time ever come when it may really begin to rain cats and dogs?

4 . Now, Earth Day is celebrated every year on April 22. A man, called Senator Gaylord Nelson Take, was determined to change the way we treated our planet. He didn’t stop his work until he had made a difference.

In 1963, Senator Gaylord Nelson wasn’t happy with the earth’s condition. He wanted to clean up the planet and solve pollution and environmental problems. As a senator, Gaylord Nelson was someone chosen by US citizens to help make laws, so he had a lot of power. He went to John F. Kennedy, the President at the time, with his concerns. The President agreed that the planet’s environment was a serious issue, so President Kennedy went around the country on a five­day tour to promote (宣传) the idea of cleaning up the planet. People began making small changes, but it wasn’t enough.

A few years later, Senator Nelson decided to put one day aside every year for the cause of saving the planet. On April 22,1970, the first Earth Day was celebrated; 20 million American demonstrators (示威者) took part in Earth Day activities. Since then, Earth Day has become an international holiday. People all over the world are doing something to make the earth a cleaner, better place. Today more than 500 million people in 164 countries participate (参与) in Earth Day festivities!

Then, what can you do to make a difference?

*Encourage your family to recycle on a regular basis. It is a good way to help the earth!

*Switch to energy­efficient light bulbs in your house to reduce the effects of global warming.

*Every glass bottle you recycle saves enough energy to run a TV for an hour and a half, while recycling an aluminum (铝) bottle can save enough energy to run your TV for three hours!

*Turn out the lights when you leave a room — unless someone’s still there!

*Use re­useable containers for your school lunches and snacks.

6 . In 1620, about half the USA was covered by forests.   Today the forests have almost gone.   A lot of good land has gone with them, leaving only sand.   China doesn’t want to copy the USA’s example.   We’re planting more and more trees.   We’ve built the “ Great Green Wall” of trees across northern part of our country. The Great Green Wall is 7,000 kilometres long, and between 400 and 1,700 kilometres wide.   It will stop the wind from blowing the earth away.   It will stop the sand from moving towards the rich farmland in the south.   More “Great Green Walls” are needed.   Trees must be grown all over the world.   Great Green Walls will make the world better.

10 . 1970 was World Conservation Year. The United Nations wanted every one to know that the world is in danger. They hoped the governments would act quickly in order to “conserve” nature. Here is one example of the problem. At one time there were 1,300 different plants, trees and flowers in Holland, but now only 866 remain. The others have been destroyed by modern man and his technology. We are changing the earth, the air and water, and everything that grows and lives. We can’t live without these things. If we continue like this, we shall destroy ourselves.

What will happen in the future? Perhaps it is more important to ask “What must we do now?” The people who will be living in the world of tomorrow are the young of today. A lot of them know that con­servation is necessary. Many are helping to save our world. They plant trees, build bridges across rivers in forests, and so on. In a small town in the United States a large group of girls cleaned the banks of 11 kilometers of their river. Young people may hear about conservation through something called “No one’s going to change our world”, which was made by the Beatles, Cliff Richard and other singers. The money from it will help to conserve wild animals.