Have you ever seen a horse with toes? Millions of years ago, horses had many toes. They had four toes on each front foot. They had three toes on each back foot. The horses were no bigger than cats.

    These small horses lived in the forest. Their many toes helped the horses run over the soft, wet ground.

    It was very hot in the forest. But the weather changed. It became cold. Many trees could not live in cold weather. The trees died and fell. Open fields took the place of forests. The sun made ground dry and hard.

    Horses began to change, too. They began to get bigger. This took a long time. On the dry, hard land, horses needed only their middle toes for running. Their middle toes became hard. After a long while, horses had only one hard toe on each foot. We call this hard toe a hoof.

    The world itself is becoming much smaller by using modern traffic and modern communication equipment(通讯设备). Life today is much easier than it was hundreds of years ago, but it has brought new problems. One of the biggest is pollution. To pollute means to make things dirty. Pollution comes in many ways. We see it, smell it, drink it and even hear it. Man has been polluting the earth. The more people, the more pollution. Many years ago, the problem was not so serious because there were not so many people. When the land was used up or the river was dirty in one place, people moved to another place. They are slowly polluting the whole world.

    Air pollution is still the most serious. It's bad for all living things in the world but it is not the only one kind of pollution. Water pollution kills our fish and pollutes our drinking water. Noise pollution makes us angry more easily.

Many countries are making rules to fight against pollution. They stop people from burning coal in houses and factories in the city, and from putting dirty smoke into the air.

Pollution by SO₂ is now the most dangerous kind of air pollution. It is caused by heavy traffic. It is sure that if there are fewer people driving, there will be less air pollution.

    The earth is our home. We must take care of it. That means keeping the land, water and air clean. And we must take care of the rise in population at the same time.

    In most parts of the world, many students help their schools make less pollution. They join environment club. In an environment club, people work together to make our environment clean.

    Here are some things students often do.

    No-garbage lunches. How many lunch bags do you throw away after lunch? Environment clubs ask students to bring their lunches in bags that can be used again. Every week they will choose the classa that make the least garbage and report them to the whole school.

    No-car day. On a no-car day, nobody comes to school in a car including the students and the teachers. Cars give pollution to us, so remember:

    Walk, jump, bike, or run!

    Use your legs! It's lots of fun!

    Turn off the water! Do you know that some toilets can waste twenty to forty cubic（立方米）of water an hour? In a year, that would fill in a small river. In the environment clubs, students mend（修理）those broken toilets.

    We love our environment. Let's work together to make it better.

    Have you ever heard of e-waste, which can be produced every day? How do you deal with your computers, MP4 players and mobile phones when they're broken or you want a new one?

    Most people just throw them away. With the development of electric industry, e-waste pollution has become a serious problem. According to the United Nations, in 2014, people around the world produced 41.8 million tons of e-waste and only recycled 6.5 million tons. The US was the biggest waster, producing 7.1 million tons. China came second, with 6 million tons.

    It's important to pay attention to e-waste. It can either be valuable or harmful, depending on how we deal with it. E-waste is a valuable urban mine. The value of the metals, like gold and silver in the waste around the world, is amazing. And the metals can be reused. But if people throw them away, the toxic chemicals can get into the earth or air, effecting the environment and people's health.

    Apple, for example, now recycle people's used products in China when they are buying new ones. The company will test and repair the used ones and sell them at lower prices. To help reduce e-waste, we can also take computers and phones to see if companies offer recycling programs.

    We all need a healthy environment, but we produce waste every day and it is harmful to our environment. Though we are young, we can still do something to help. In fact, even the simplest everyday activities can make a real difference to the environment. Here are some ideas for you to live a green life.

    Remember these three words; reduce, reuse and recycle.

    Reduce means" use less". Don't waste things. This saves money and reduces pollution and waste going into the environment. Before we buy something new, think if it is really necessary or maybe the old one will be just as good! When we do buy thing, choose local products if possible, and try not to buy too many things from abroad.

    Reuse mean" use again". Use things for as long as possible. When we buy things, make sure that they last a long time. We should take care of them so that they will last, and we should repair them if we can instead of throwing them away and buying new ones. Don't use a paper cup or a paper bag. It's better to use a china cup(瓷杯) and a lunch box because you can use them again.

    Recycle means" change things into something else". Although it takes energy to change something into something else, it's better than throwing things away or burning them. Find out what can be recycled in your neighbourhood and take part in recycling programmes. We should also buy products made from recycled materials, such as recycled paper, to help save trees.

Title:{#blank#}1{#/blank#}to Live a Green Life

    Big data (数据) is a lot of sets of information that are put together so they can be used by a computer program. The computer program looks for different kinds of answers or patterns in the data. Big data can have different kinds of information from many sources, such as information that comes from schools, social media sites, companies, and governments. One set of data can have people's names and addresses. Another set can have what they like, where they go to school, and how much time they spend on the computer.

    Big data can be used in many ways. The government uses it to understand how many people travel on buses or trains. This information is then used to make bus or train systems better. Some schools use big data to understand which children may need extra help in class. The teacher can then give certain students more help or support so those students can succeed in school. Companies use big data, too. It helps them understand who buys their products. For example, one company uses weather data to see when people eat the most ice cream.

    Big data can be used for good reasons. Some hospitals use big data to predict if a baby who is born too early will get sick. The hospital can then take extra steps to take care of that baby so he or she does not get sick. Big data can also be used for bad reasons. It can be used to predict which kinds of people are likely to break the law or hurt others, even if they have not done anything wrong.

    How can big data be used for good and bad things? It is because the computer programs used to look at big data and understand it are written by people. People think a certain way. Because they think a certain way, they build a model of those ideas. These ideas are then used to look at the data. Sometimes, these ideas are helpful for people or businesses. Other times, bad ideas can cause problems for certain groups of people.