Think about vitamin D when you're catching up on summer rays. It's sometimes called the “sunshine vitamin” because it's produced in your skin in response to sunlight. Vitamin D is a fat-soluble (脂溶性的) vitamin in a family of compounds that includes vitamins D-1, D-2, and D-3. It can affect as many as 2,000 genes in the body.

    Vitamin D has several important functions. Perhaps the most vital are regulating the absorption of calcium and phosphorous（磷）, and promoting normal immune system function. Getting enough vitamin D is important for normal growth and development of bones and teeth, as well as improving resistance against certain diseases.

    In addition to its primary benefits, research suggests that vitamin D may also play a role in: reducing your risk of multiple sclerosis（多发性硬化）, according to a 2006 study published in the Journal of the American Medical Association decreasing your chance of developing heart disease, according to 2008 findings published in Circulation helping to reduce your possibility of developing the flu, according to 2010 research published in the American Journal of Clinical Nutrition regulating mood and warding off depression losing weight or preventing heart disease.

    How do you get it? Your body produces vitamin D naturally when it is directly exposed to sunlight. A little can go a long way. All you need is 10 minutes a day of midday, pre-sunscreen sun exposure,especially if you have fair skin. Besides getting vitamin D through sunlight, you can also get it through certain foods and supplements to ensure adequate levels of the vitamin in your blood.

    An artist in Oakland, California is using his skills to help the homeless. Greg Kloehn builds very small shelters that make life on the streets a little more comfortable. The structures offer the homeless some safety and protection from bad weather. Each little house also has wheels on the bottom so it can go wherever its owner goes.

    Greg Kloehn has given away at least 20 tiny houses. Several are on the roadside near an active railroad. On a recent day, Mr. Kloehn stops at one to visit Oscar Young. The two men hug. Inside his little shelter Mr. Young gets relief from cold nights on the streets. Mr. Kloehn also visits Sweet-Pea, another friend who also lives in one of the little homes the artist built. She says it keeps her safe and protects her belongings.

    In the mornings, Mr. Kloehn searches the streets for building materials. He gathers what he can and takes it to his studio. There, he puts the houses together. Empty coffee bags become roof material. A washing machine door and refrigerator part become windows. Nails, screws and the sticky glue hold all the pieces together. The artist also attaches a small electrical device to the house. The device is powered by the sun.

    Some of the people living on the streets once had normal houses of their own. But some of the people say they have learned to live with less and they are thankful to that man.

    Mr. Kloehn says his work is not a social project. He says he is just someone using his skills to help his homeless neighbors.

    The US will have a new president this fall. Voters will decide between the Democratic candidate (候选人), Hillary Clinton, and Donald Trump of the Republicans.

    But the voting is not a must for each person in the US. So quite a lot of people choose not to vote, especially the young generation. According to Fox News, one-in-five young voters between the ages of 18 and 35 said clearly that they wouldn't vote for either of the two candidates. Just 12 percent of voters aged 35-54, and only nine percent of voters aged 55 and older said the same thing.

    This is not only because young people don't like Clinton or Trump, according to the Fortune magazine. The truth is that they are traditionally less likely to vote than their parents.

    “Young people are not at an age in their life when they think politics or government has anything to do with them,” said Rodd Freitag, a political science professor at the University of Wisconsin-Eau Claire, US. “But for the older age groups, they have a home, they pay taxes (税), they care about schools and the community.”

    Many believe that the civic (公民的) education of an American youth is another reason why they don't vote.

    Students usually just do community services like cleaning the neighborhoods. This means they haven't learned how to link real life problems to politics through voting, according to Christopher Beem, a politics professor at the Pennsylvania State University.

    He said the country needs to help young people learn how to take part in politics and get them to see that they can make a difference.

People aren't walking any more—if they can figure out a way to avoid it.

    I felt superior about this matter until  the other day I took my car to mail a small parcel. The journey is a matter of 281 steps. But I used the car. And I wasn't in ay hurry, either, I had merely become one more victim of a national sickness: motorosis.

    It is an illness to which I had thought myself immune（免疫的）, for I was bred in the tradition of going to places on my own two legs. At that time, we regarded 25 miles as good day's walk and the ability to cover such a distance in ten hours as sign of strength and skill. It did not occur to us that walking was a hardship. And the effect was lasting. When I was 45 years old I raced –and beat—a teenage football player the 168 steps up the Stature of Liberty.

Such enterprises today are regarded by many middle-aged persons as bad for the heart. But a well-known British physician, Sir Adolphe Abrhams, pointed out recently that hearts and bodies need proper…… is more likely to have illnesses than one who exercises regularly. And wlaking is an ideal form of exercise— the most familiar and natural of all.

    It was Henry Thoreau who showed mankind the richness of going on foot. The man walking can learn the  trees, flower, insects, birds and animals, the significance of seasons, the very feel of himself as a living creature in a living world, He cannot learn in a car.

    The car is a convenient means of transport, but we have made it our way of life. Many people don't dare to approach Nature any more; to them the world they were born to enjoy is all threat. To them security is a steel river thundering on a concrete road. And much of their thinking takes place while waiting for the traffic light to turn green.

    I say that the green of forests is the mind's best light. And none but the man on foot can evaluate what is basic and everlasting.

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    The EP will not reduce oxygen in the room. With other heaters, you'll notice that you get sleepy when the heat comes on because they are burning up oxygen.

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    How do you get a man to do his share of the housework? If you are like most women, you've faced this question the hard way.

    A man will enjoy a clean, orderly house, but he usually won't make the effort to clean or organise it. This doesn't mean that a woman has to do all the housework; she may have to manage many of the household duties, and request her partner's participation(参与). A woman can often say that men and women should take equal responsibility(责任) for housework.

    Very few men are raised to be fully responsible for housework, and many men look on housework as women's work. On the other hand, most men will readily work around the yard, make repairs and complete projects on weekends or evenings, and it's important that you give your man appreciation(欣赏) for those things, too. Most men will take on a little housework around the house if asked politely. They are even more likely to do housework if they can choose what they want to do, and do it without being monitored(监视).

    Here's the key: men want to feel that they are doing housework either because they want to do a task, or because they simply want to please their women. Men are much less likely to take on household tasks they consider uninteresting and unimportant. In other words, men are likely to do a household task just for the good of the house.