A recent study found people's lives are made shorter in North China. It is showed the life expectancy(平均寿命) had been cut down by 5.5 years there. Researchers（研究者）think that the heavy air pollution in China should be to blame(承担责任). It's really the truth. Our government has already done something. However, it doesn't seem to work so well.

    “Air pollution in China is doing harm to people's health. The harm is much more serious than we can imagine,” said Chen Yuyu of Beijing University, one of researchers of this study.

    Dirty air brings serious problems in North China. In January this year, the air pollution was worse than that in other places. That was caused by rising temperature and waste gas（气体）from coal heating（燃煤）.

    Chinese government should strongly fight with air pollution. They should think of more proper ways to deal with the problem. People should be encouraged to take buses, ride bicycles or walk, instead of driving cars. The factories that pollute heavily should be closed.

    “We need to improve our environment, although it might be expensive. Protecting our environment means protecting ourselves,” Li Hongbin, another researcher of the study said.

A

    What picture do you have of the future? Will life in the future be better, worse or the same as now? What do you hope for about the future? Scientists think that life will probably be very different in 2050.

    First of all, it seems that people won't use TV channels by 2050. Instead, people will choose a program from a "menu" and a computer will send the program directly to the television.

    Water will become a very serious problem. We'll need much more water, but there won't be enough. Some scientists think that water would be the cause of war.

    Cars will run on new clean energy and they will go very fast. And there won't be any accidents with the help of computers. On the other hand, space planes will take people around the world in two hours.

   Robots will work in factories instead of people. Many factories have already used robots. Big companies prefer robots—they do not ask for money, and they work for 24 hours a day.

    In a word, by 2050, our life will change a lot and our future will be quite different from now.

    27 world records were broken during the 2016 Summer Olympics. They fell in swimming running weightlifting and a number of other sports. But how do athletes continue to get better, jump longer, run or swim faster? Although scientists say that athletes have reached their limits (极限), records continue to fall. In almost every sport, athletes have become better since the Olympic Games begin.

    One reason is that and more people than ever before have access to sports and exercise. They start at an earlier age and can compete longer in their sport. In schools more and more natural talents can be discovered.

    Besides, athletes can train full-time instead of training after works. As medicine improves, athletes can stay in competition for a longer time and overcome injuries (损伤) faster. Many top athletes achieve their best results later on in their careers. Technology has also helped improve scores.

    One of the most important reasons, however, is the human mind. We always want to be better and faster that someone else. It can release (释放) great power in our body.

    So, where are limits? One of the most difficult questions to answer is how fast a human being can run. Many years ago, nobody thought a person could ever run within 10 seconds in the 100-metre race. But the record was broken at the 1968 Mexico City Olympics. A t the moment Sustain Bolt is the fastest man on Earth at 9.58 seconds. Scientists say that 9.48 may be the limit, but, who knows, maybe some runners will one day run within 9 seconds.

    What does it mean to be green? "Green" is more than just a color. It also means taking special steps to protect the environment — the water, the land, and the air we breathe. Why green? Plants are green, and without them the earth wouldn't be such a lovely home for us human beings.

    Sometimes people call our society a "throwaway society". That means we are always throwing away old things and buying new ones. Many times, if you no longer need something, someone else just might need it. For example, if your brother is old enough not to play with his plastic bike, why not give it to another family who has a little kid so that they don't need to buy one? And one less large plastic toy doesn't need to be produced.

    Recycling （回收利用）has never been easier. Many organizations will pick it up right in front of your house and some towns even require （要求）it. Tell your mom or dad you want to become "Chief of Recycling" for your family. Now that you know what things you can recycle, find a place to keep them. Make sure you encourage everyone in your house to think whether things can be reused or recycled before they're thrown away.

    Almost everyone likes traveling. But next time before you travel around the world, take a look at your own backyard. Is there a place where you could plant a tree or put in a little fruit or vegetable garden? If so, get there and get your hands dirty. Then you can watch with pride as your tree takes root, and your garden plants grow into big plants full of ripe, red tomatoes or tiny, juicy blueberries. Who knew being green would taste so good?

    It's every parent's worst nightmare: there's a fire in the house the alarms are beeping, but the children are sleeping on. Now scientists have found a better way to rouse slumbering youngsters. Researchers in the US have discovered that playing a child a recording of his mother's voice is about three times more likely to wake him up than a traditional alarm.

    Writing in the Journal of Pediatrics, Smith and colleagues report how they compared the effects of four different smoke alarms on 176 children aged between 5 and 12 years old, none of whom had hearing difficulties or were taking any medication that affected their sleep. While one alarm featured a high pitched beeps he sort of commonly found in households the other three featured the voice of the child's mother calling either the child's name, giving instructions such as: "Wake up! Leave the room or both. Each child slept in a lab-based room that resembled a real bedroom.

    The results show that vocal alarms appear to be more effective than high-pitched beeps. About 90% of children woke for a voice alarm compared with just over 53% for the traditional alarm

    "High pitched beeping alarms don't wake up children well at all under about 12 years of age." Said Dr Gary Smith, a co-author of the research from the Nationwide Children's hospital in Ohio, although he said at present it is not known why He said it was important to look at developing better alarms

    Prof Niamh Nic Daeid, director of the Leverhulme Research Centre for Forensic Science at the University of Dundee, said the research found a human voice combined with a low frequency pulsing tone was far more effective in waking up children than a traditional high-pitched alarm. She also noted that more work was needed to explore whether other familiar sounds, such as a dog barking, might also prove effective in rousing children.