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We've all heard of mermaids. They are the beautiful half-human, half-fish creatures(生物). They have the head and body of a human and the tail of a fish. We also know that mermaids only exist in fairy tales. But where did all the stories about these creatures come from? If you have ever seen a manatee, then you might have an idea.
Manatees, which are also called sea cows, are mammals(哺乳动物) that live in the sea. Since they are mammals, they have to swim up to the surface to breathe air. Many people believe that the story of the mermaid began with the ancient sailors who saw the manatees putting their heads out of the water to breathe. Because manatees are upright when they do this, it looks like they are standing. If a sailor saw a manatee doing this from far away across the sea, it is possible that the sailor would mistake the manatee for a creature that is half-human, half-fish.
Mermaids are described as having very long hair. This is probably because manatees like to swim up to the surface of the water in areas where there is sea grass. Manatees eat all kinds of plants in the sea, including sea grass. The sea grass around the manatee's head when they eat could create a picture of long hair.

Manatees also have powerful tails that are very similar to the fish-like tail of a mermaid. The sailors probably watched manatees come up for air and then swim back below the surface, using their paddle-shaped tails. This would explain why the sailors thought mermaids had fish-like tails.

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    The Earth is our home; we must take care of it. This means keeping the land, air and water clean. Pollution is a dirty word. To pollute means to make things unfit or unclean to use. Pollution comes in many ways. We see it, smell it, taste it and drink 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 were 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 population and the development of industry(工业)have changed that. Man is slowly poisoning (毒害) his environment. 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.

    Five hundred years ago, potatoes grew in South America. They were an important food for the people who lived in these high mountains. In other parts of the world, however, people didn't know about potatoes.

    The Spanish came to South America in the 1500s. They learned of potatoes and took some back to Spain. By 1570, people grew white potatoes in parts of Spain. By 1580, people in Italy were also growing potatoes.

    From Spain, potatoes travelled to France. In France, however, people were afraid to eat this new vegetable. They thought it was bad for health. Then the King of France tried to make his people eat potatoes. But for many years, the French still refused to eat potatoes.

    Potatoes reached England in a different way. In 1586, the English explorer(探险家) Drake stopped in Colombia. There he probably picked up some potatoes and took them back to England. At first, the English refused to eat potatoes, too. They used potatoes to feed their pigs and chickens.

    From England, the potato travelled to Ireland. The potato grew well in the poor soil of Ireland and soon it was an important food for the people in Ireland.

    In the early 1700s, Irish people brought potatoes to North America. By 1750, many people in New England were growing and eating potatoes.

    Mica and her little sister got a tree house this year. "I'm Mica! I love my tree house!" This $28,000 tree house is a gift from their parents. Almost three metres above the ground, the platform (平台) was built between two large trees. "One of the things I really wanted was a little door within the big door. If you go up, you'll find that there is a door handle, which is of the kids' height. And there is an adult size door as well. I told the designer to make it feel like a secret hideout (躲藏处)," said Mica's mother Keenan.

    Bala Sundar and his wife came to America 20 years ago. Unlike Keenan and her husband, who bought a tree house for their daughters, the Sundars got one for themselves. "We wanted to have a regular place where we can relax. So we bought it," he said. With beds, tables and windows, it's a welcoming, comfortable space to spend a summer night.

    Both of these amazing tree houses were created by Dan Wright. He's the founder of Tree Top Builders Inc., and has built more than 400 tree houses since he started the company in 2003. "I think the sense of freedom and independence is why Americans can resonate (共鸣) with tree houses. They get people up off the ground and, for kids, their parents can't reach them anymore. They are up looking down, getting a new perspective on life," said Wright.

    Paulina Cortes is a teacher in San Jose, California. One day, she handed out masks (面罩) to farm workers in Lodi. She volunteered to do this because the air quality (空气质量) is still poor after a big fire.

    "I just got home and feel really tired now. Today I spent my day in Lodi handing out masks to farm workers," she wrote on the Internet. "I raised some money. Then I drove through San Jose and all the way to Salinas to buy enough masks I needed. This is important. The story here isn't that I handed out masks; it's that there are hundreds of people who are working in dangerous environments with no protection (防护). And no one even knows about it."

    Paulina also put some photos on the Internet, and they were picked up by the news. Many people were surprised at the news, and they knew what happened to those farm workers for the first time.

    The next day, Paulina added, "I traveled through Lodi and Stockton not just to hand out masks, but to help the farm workers understand the pollution. In Lodi yesterday the workers were picking fruit in such dangerous environments. None of them even knew this. Not too far from our homes, hundreds of people are working in these environments. I will buy more masks and send them to a Stockton farm worker. He helped me hand out masks yesterday."

    Thank you, Paulina, for caring and trying to make a difference.