Monarch butterflies from eastern Canada make the most amazing journey in the insect world. Each year, this butterfly travels about 3000miles to its winter home in central Mexico(墨西哥). How can it fly so far? And why does it make this long and dangerous trip? Scientists still don't have an answer.

 For many years, people in Mexico wondered where the orange-and-black butterflies came from every winter. Then, in 1937, a scientist started to follow and study the butterflies. For the next 20 years, he discovered that one butterfly started its journey in Canada. Four months later, it arrived in Mexico.

 The length of the butterflies find their way back to the same place? Another amazing thing is that the butterflies always return to the same area in central Mexico.

 How do the butterflies find their way back to the same place? This is an interesting question because only every fourth generation(代) makes the trip south. In other words, the butterfly that travels to Mexico this year is the great-great-grandchild of the butterfly that traveled there last year.

 Each year, four generations of a Monarch butterfly family are born. Each generation of the family has a very different life. The first generation is born in the south in late April. It slowly moves north, reproduces(繁衍), and then dies. On the trip north,two more generations are born, reproduce, and die. Each of these generations of butterflies is born. This generation has a much longer life. It lives for about eight months. This generation of butterflies makes the amazing journey back to the winter home of its great-great-grandparents. The butterflies spend the winter there, and in the spring they reproduce and then die. Their offspring will be the first generation of the next circle of life.

 Today, people are still studying the Monarch butterfly. But they are not clear about everything.

    Ask someone what they have done to help the environment recently and they will almost mention recycling. Recycling in the homes is very important. However, having to recycle often means we already have more products than we need. We are just dealing with the results of that over-consumption in the greenest way, but it would be much better if we did not bring so many goods home.

    The total amount of packaging（外包装）has increased by 12% between 1999 and 2005. It is 1/3 of a home's waste in theUK. In many supermarkets, food products are packaged twice with plastic and paper. Too much packaging is doing serious damage to the environment. The UK, for example, is running out of land because of this unnecessary waste. If such packaging is burnt, it gives off greenhouse gases which go on to cause the greenhouse effect. Besides, the plastic from the package puts some creatures indanger, especially birds and fish.

    Recycling helps, but the recyclingitself uses energy. The solution is not to produce such waste in the firstplace. Food waste is a serious problem, too. Too many supermarkets encourage customers to buy more than they need. However, few of them have the idea that this cannot continue. For example, supermarkets should encourage customers to reuse their plastic bags.

    But this is not just about supermarkets. It is about all of us. We have been used to the idea that packaging means excellence while anything unpackaged is of poor condition. This is especially true of food. But this idea has spread to other products, which often have farmore packaging than necessary.

    There are signs of hope. As more of us recycle, we are beginning to realize just how many unnecessary goods are collected. We need to face the waste of our consumer culture, but we have amountain to climb.

What is your favorite color? Ask famous persons like Cate Blanchett, Scarlett Johnson, and Bono (singer for the band U2), and maybe they will say “green.” That's not because these artists like the color green best. Instead, they are interested in green fashion.

       Green fashion is about making (and wearing) clothes that are good for humans, animals, and the Earth. In the past, green fashion made people think of ugly clothes. But today, green fashion is different. It is about looking good and caring about the Earth and other people. You can have interesting clothes and be green.

Around the world, green fashion is becoming popular. For example, the U.K. company People Tree sells men's and women's clothing and accessories(配搭物). They are made from natural fabrics(织物) like cotton and wool. Workers who make the clothes are from countries like Kenya(肯尼亚), and Bangladesh(孟加拉国). People Tree pays the men and women good money for the clothes they make.

Singer Bono and his wife also started a clothing company called EDUN. When the clothes are sold, EDUN uses most of the money to help people around the world.

    Why do plants grow in some places and not in others? Why does some land have so many plants growing on it, while other land has almost no plants growing on at all?

    To grow, plants need some things. One is warmth. In very cold places, almost nothing grows, Plants also need water. In very dry parts of the Earth, only a few unusual plants can grow. That's why dry deserts(沙漠）almost don't have trees or grass.

    Plants must also have a place in which to put down their roots（根）and grow. They find it difficult to grow on hard land. The town is on hard land. The plants here can only grow in the soil（土壤）between the cracks of the stones.

    Another thing plants must have before they can grow is food.

    What will happen if we try to make things grow on the sandy（有沙的）beach? A few plants, such as beach grass, will grow in sand, but most plants won't. Even if（即使）the weather is warm enough and we water the plants each day, many of them will die because the sand on this beach has almost no food for plants.

    When we think of paper, we think of newspapers and books. But there are many other uses. Only half of the world's paper is used for books and newspapers.

    Paper is very good for keeping you warm. You have perhaps seen homeless men sleep on a large number of newspapers. In Finland, it is sometimes-40℃ in winter. The farmers wear paper boots(靴子)in the snow. Nothing could be warmer.

    Each year, more and more things are made of paper. We have had paper cups and plates for a long time. But now we hear that chairs, tables, and even beds can be made of paper. Besides paper boots and shoes, you can wear paper hats, paper dresses, and paper raincoats. When you have used them once, you may throw them away and buy new ones.

    The latest use of paper seems to be paper houses. These are not small houses for children to play in, but real, big houses for people to live in. You can buy a house with three rooms for about 500 dollars. You can put it up by yourself in a few hours, and you can use it for about five years.