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.

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    Research proves that nearly half of the cancers diagnosed(诊断) in the UK each year-over 130, 000 in total- are caused by life choices that include smoking, drinking and eating the wrong things.

    Tobacco(烟草) is the biggest factor, causing 23% for cases in men and 15.6% in women, says the Cancer Research UK report. Next comes a lack of fresh fruit and vegetables in men's diets, while for women it is being overweight. Lead author of the report, Professor Max Parkin, said: "Many people believe cancer is related to fate or in the genes(基因), and that it depends on luck whether they get it or not. Looking at all the evidence, it is clear that around 40% of all cancers are caused by things we mostly have the power to change."

    For men, the best advice appears to be: stop smoking, eat more fruit and vegetables and cut down on how much alcohol you drink. For women, again, the best advice is to stop smoking, but also watch your weight.

    In total, 14 lifestyle and environmental factors, such as where you live and the job you do, cause 134, 000 cancers in the UK each year.

    Some risk（风险） factors are well founded, such as smoking's link with lung cancer. But others are less well recognized. For stomach cancer, a fifth of the risk comes from having too much salt in the diet, data suggests. Some cancers, like mouth and throat cancer, are caused almost entirely by lifestyle choices. But others, like gall bladder cancer(胆囊癌), are largely unrelated to lifestyle.

    Public Health Minister, Anne Milton, said: "By making small changes you can cut your risk of serious health problems- giving up smoking, watching you drink, getting more exercise and keeping an eye on your weight."

    Is there intelligent(有智力的) life on other planets(行星)? For years, scientists said "No." or "We don't know." But today this is changing. Seth Shostak and Alexandra Barnett are astronomers (天文学家). They believe intelligent life exists somewhere in the universe. They also think we will soon contact these beings(人；生物).

    Why do Shostak and Barnett think intelligent life exists on other planets? The first reason is time. Scientists believe the universe is about 12 billion years old. "This is long enough for other planets to have intelligent life," say Shostak and Barnett. The second reason is size——the universe is huge. "Tools like the Hubble Telescope (哈勃望远镜) have shown that there are at least 100 billion galaxies (银河系) ," says Shostak. "And our galaxy, the Milky Way, has at least 100 billion stars. Some planets going around these stars might be similar to Earth. "

    In the past, it was hard to look for signs of intelligent life in the universe. But now, powerful telescopes (高倍望远镜) allow scientists to discover smaller planets--the size of Mars or Earth--in other solar systems (太阳系).These planets might have intelligent life.

    Have beings from space already visited Earth? "Probably not," says Shostak. "It's a long way away. However, intelligent beings may contact us in other way, such as radio signals(信号). "In fact, they may be trying to communicate with us now, but we don't have the right tools to receive their messages. However, this is changing. By 2025, we could make contact with other life forms in our universe and we might help each other.

    Many people are trying to save the earth with special days like "Meatout Day", "Earth Day" and "Buy Nothing Day".

    "Meatout Day" is on March 20. Many people around the world don't eat any meat for one day. In this way, they'll get healthier and reduce greenhouse gases (减少温室气体).

    "Earth Day" is on April 22nd. Many people all over the world try to do something green on this day. In Italy, people don't use plastic bags. In Canada and Norway, people ride bicycles and don't use their cars. In the USA, people dress up like plants and animals to dance in Times Square, New York.

    "Buy Nothing Day" is usually on the fourth Friday in November. On this day many people don't buy anything. "Buy nothing" means "make no rubbish". When you make less rubbish, you can make a cleaner earth.

    Do you want to join them? Then you can remember these special days and do something green.

    The coffee shop Starbucks will give people a discount if they bring their own cups. It wants to cut down on the number of paper cups that are put in the rubbish bins. It is part of a two month experiment in cafes in England. Starbucks wants to reduce waste and recycle more, The president of Starbucks in the UK said, "We are very happy to increase recycling rates(比率)，and reusable cups are a key part of our waste reduction plan." Bosses will decide later if they will continue the discounts. People who bring their own cups will not get a discount on the cafe's cheaper filter coffee.

    The problem of paper cups has been in the news a lot. Around seven million cups are thrown away every day. Reporters say that some cafes lie about how many paper cups they recycle. The reporters say the cafes do not recycle as many cups as they say. Customers wrongly believe that a coffee shop is environmentally friendly. Less than one in 400 paper cups at coffee shops are recycled. A coffee drinker said she would bring her own cup. She said, "I am so sad that cafes recycle so little. I thought they were more responsible."