You may think that light pollution isn't something extraordinarily important. You may believe that every other type of pollution has a larger impact on the environment that light pollution does. But light pollution is serious.

    Light pollution, or “sky glow”, is the glow you can see at night above cities and towns. Light pollution is a problem that has been accompanying man ever since he started his first fire some 15,000 years ago. Light pollution is the light that comes from streetlights, buildings, parking lots and any other source of light that is reflected or directed into the atmosphere.

    Urban light pollution means that one-fifth of the world's population can no longer see the Milky Way(银河) with the naked eye(肉眼). Many city kids, even if they did look through the orange smog above their heads, would probably see only a handful of stars. We have lost our view of the stars, and we have mucked up our  night-time environment as well. Astronomers are calling for the dark places on Earth to be preserved as national parks.

    Lots of people find the ever-brightening night annoying, and animals that are programmed to prefer the dark may avoid a brightened habitat. Sea turtles can get lost searching for a beach to lay eggs, and their hatchlings(孵化的幼仔)may confuse over-lit beachfront resorts(度假胜地) for the ocean horizon, wasting precious energy needed to find the sea and escape predators(食肉动物). Because their necks aren't yet long enough to see things far away, baby turtles rely on the mirror image of the moon to guide them to the sea, to begin their new life. A car may even hit a particular turtle, which was thinking the light from a nearby city was moonlight reflecting off the ocean waves. Birds that live in and around cities can die because of sky glow, too. The bright lights can blind them, leading to countless collisions with buildings and other tall structures.

    On an individual level, people can help reduce much sky glow by using lighting only when necessary. The stars above us are priceless heritage— for not only for astronomers but for all humans. More of our children should be able to look up at night and see the Milk Way.

    Cleaning your plate may not help feed hungry children today, but the timeworn advice of mothers everywhere may help reduce food waste from the farm to the fork, help the environment and make it easier to feed the world's growing population.

    Hard data still being collected, but experts in Chicago said about 30% to 50% of the food produced in the world goes uneaten. The average American throws away 33 pounds of food each month—about $40 worth, which means each person throws away almost 400 pounds of food. The US Department of Agriculture says that 23% of eggs and an even higher percentage of produce ends up in the trash.

"We forget we have all these fresh fruits and vegetables, and at the end of the week we have to throw them away", said Esther Gove, a mother of three young children in South Berwick, Maine. "Now, I don't buy as much fresh produce as I used to."

    But the effect of food waste arrives far beyond the kitchen. Agriculture is the world's largest user of water, a big consumer of energy and major emitter of greenhouse gases during production. Experts say reducing waste is a simple way to cut stress on the environment and can ease pressure on farmers, who will be called on to feed an expected 9 billion people around the world in 2050, compared with nearly 7 billion today.

    No matter how sustainable (可持续的) farming is, if the food's not getting eaten, it's not sustainable and it's not a good use of our resources. In richer nations, fruit and vegetables end up in the trash because they aren't pretty enough to meet companies' standards, have gone bad in a home refrigerator or aren't eaten at a restaurant. In developing countries, much food spoils before it gets to market due to poor roads and lack of refrigeration. High food prices are another reason, since some people can't afford the food that's produced.

    Smiling is a great way to make yourself stand out while helping your body to function better. Smile to improve your health, your stress level, and your attractiveness.

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    We are drawn to people who smile. There is an attraction factor. We want to know a smiling person and figure out what is so good because anxieties can push people away, but a smile draws them in.

Smiling changes our mood

    Next time you are feeling down, try putting on a smile. {#blank#}2{#/blank#}Smiling can trick the body into helping you change your mood.

Smiling relieves stress

    Stress can really show up in our faces. Smiling helps to prevent us from looking tired or worn down. {#blank#}3{#/blank#}The stress should be reduced and you'll be better able to take action.

Smiling lowers your blood pressure.

    When you smile, there is a measurable reduction in your blood pressure. Give it a try if you have a blood pressure monitor (血压计) at home. Sit for a few minutes and take a reading. Then smile for a minute and read it again while still smiling. {#blank#}4{#/blank#}

Smiling lifts the face and makes you look younger.

The muscles we use to smile lift the face, making a person appear younger. Don't go for a face lift, just try smiling your way through the day — you'll look younger and feel better.

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    Try this test: Smile. Now try to think of something negative without losing the smile. It's hard. When we smile, our body is sending the rest of us a message that “Life is good!"

A. Smiling helps you stay positive.

B. Smiling makes us attractive.

C. Do you notice the difference?

D. Smiling can bring you luck and sorrow.

E. When you are stressed, take time to put on a smile.

F. There's a good chance that your mood will change for the better.

G. As long as you try smiling daily, it can make you look younger.

    Green spaces within and around city schools improve the mental development of young children, a study has found. The findings may partly be explained by reduced exposure to traffic pollution, experts believe. Other influences could include the psychological effect of having views of fields and trees rather than roads and buildings.

    The Spanish researchers found each degree of increase in surrounding greenness led to a 5% improvement in the development of short-term, or working memory over a period of one year. It also improved the progress of "superior working memory”—the ability to update memories. with changing information—by 6%，and reduced inattentiveness. Computer analysis suggested that carbon from traffic might account for up to 65% of the trend.

    The researchers carried out mental performance tests on 2, 593 children attending 36 primary schools in Barcelona every three months for a year. Over the study period, participants' working memory increased by an average of 22.8%, and superior working memory by 15.2%, while inattentiveness decreased by 18. 9%.

    The researchers wrote, "Approximately one half of the world population lives in cities, and by 2030, three in five persons will live in urban areas worldwide, Urban areas are a network of non-natural built-up structures with increased pollutant levels and less green environments. Children's exposure to these pollutants has been associated with harmful impacts on their mental development. Our findings suggest a beneficial impact of greens paces exposure on mental development. "

    British experts said the study was interesting, but pointed out some limitations. Professor Andy Jones, from Norwich medical school, said, “The measure of green space used was the number of plants in the neighborhoods of the children and their schools. It was not a direct measure of usable green spaces, like public parks, although they will be included. " Dr Ross Cameron, at the University of Sheffield, said, “The authors suggest a causal link between air quality and green space. They admit, however, that this factor only seems to explain part of their correlations(相互关系), ”

    Many people trying to sell homes find that an increase in home prices has turned the market in their favor. But sellers can still get the short end of the deal if they aren't careful. Here are a few tips for you:

    Don't test your luck. Of course you think anyone who moves into your lovely home should be willing to pay top dollars, especially if you've recently invested in some improvements. But listing a home at a price that's too high above the market price could turn away some buyers.

    Buyers noticing that the home still hasn't sold may begin to assume there's something wrong with the house and use that as a reasonable excuse for offering a lower price. And if a home hasn't received any offers after two weeks, it might be time to reset the price.

    A price that's too low can bring about an undesired outcome. Listing your home at or slightly below the market price can have the effect of drawing in a large group of buyers and increase the chances that a home will receive multiple offers. But setting the price too low comes with several risks. One possibility is that buyers will get skeptical of the home that is listed for $ 15,000 to $ 20,000 less than similar homes in the area, especially if it's not properly marketed. Once again, people might assume there is something wrong with the home and may not bother to look at it.

    Spy on the competition. Going to other people's open houses can give you a better sense of how your home compares to others on the market. Check out the decoration in their kitchens, the size of their backyards and use the information to figure out where your home should fit in the range of the price. But don't set your pricing just on what you see elsewhere.

    What's it like to become a music star with millions of fans? These young artists know the feeling. Over the course of their short careers, they have attracted the attention of the biggest stars in the world and taken home prizes from major shows. For now they're just kids that everyone in music is watching. Check out the next generation of stars below.

    FIFTH HARMONY

    The 1990s was a brilliant period for girl groups. But after that few groups have been able to make much of an influence. This doesn't seem to bother Fifth Harmony, who landed the biggest hit of their career in 2016 with "Work from Home", a pop song that encourages everyone to ask for leave more often. When it climbed to No.4 on the Billboard Hot100, it was the first time that a girl group had entered the top 5 in the past ten years.

    LORDE

    It's been four years since the release of Born Heroine — the hot selling CD that made her a 16-year-old global sensation and the spokeswoman for a new generation of smart, strong-minded, creative female pop artists. She contributed to The Hunger Games soundtrack (插曲) in 2014, and for this time setting foot in Hollywood production also brought her more opportunities in her following career.

    TROYE SIVAN

    You might recognize the rising star Troye Sivan from YouTube, where he's been uploading videos since he was 12 and his channel already has millions of fans, or from the movies, where he played the role of young Wolverine in X-Men Origins: Wolverine.