A warm drink of milk before bed has long been the best choice for those wanting a good night's sleep. But now a study has found it really does help people nod off—if it is milked from a cow at night.

       Researchers have discovered that “night milk” contains more melatonin(褪黑激素), which has been proven to help people feel sleepy and reduce anxiety.

       The study,by researchers from Seoul, South Korea, involved mice being fed with dried milk powder made from cows milked both during the day and at night.

       Those givennight milk, which contained 10 times the amount of melatonin, were less active and less anxious than those fed with the milk collected during daytime, according to the study published in The Journal of Medicinal Food.

       Night milk quickened the start of sleep and caused the mice to sleep longer.

       While the effect of cows milk harvested at different time has not been tested on humans up to now, taking melatonin drugs has been suggested to those who are struggling to fall asleep at night.

Previous studies have also indicated that milk can be excellent for helping sleep because of the calcium content, which helps people to relax.

       Milk is also sugar-free and additive-free with nutritionists recommending skimmed milk as the best choice before bed as it is the least fattening. The more fat you take in before bedtime, the greater burden you will put on your body at night.

    Taking a math test can be pretty stressful. Even if you know the material, you can still get the problem wrong. Knowing how to go through your math test and check your work can save you from handing in a test full of mistakes that can be avoided. {#blank#}1{#/blank#}

Write it out

    You can also check a math problem by writing everything out on paper. {#blank#}2{#/blank#} Writing out math problems reduces your chances of missing anything to the lowest possible level, which is a common cause of incorrect answers.

{#blank#}3{#/blank#}

    Make sure your answers work by doing the opposite procedure of what your problem calls for, including the answer you got the first time around. In other words, you would use the opposite of this addition problem—subtraction (减法)—to determine whether or not your answer is the correct one.

Plugging in

    You may find that a variable isn't good enough or have a problem where you have to solve for a variable (变量). {#blank#}4{#/blank#} This is the only real way to assure yourself that the answer you've found is correct.

Check for a reasonable answer

    {#blank#}5{#/blank#} For example, if you get an answer in the millions and you know it should be in the thousands, you've likely misplaced a point. Go back through the work on your paper to make sure all of your formulas and calculations are correct. If everything looks okay, do the problem again and compare the result of the second try to what you've got on the first try.

    {#blank#}1{#/blank#}We achieve it actively by direct experience, by testing and proving an idea, or by reasoning. We achieve knowledge passively by being told by someone else. Most of the learning that takes place in the classroom and the kind that happens when we watch TV or read newspapers or magazines is passive. Conditioned as we are to passive learning, it's not surprising that we depend on it in our everyday communication with friends and co-workers.{#blank#}2{#/blank#} It makes us tend to accept what we are told even when it is little more than hearsay and rumor.

    Did you ever play the game Rumor? It begins when one person writes down a message but doesn't show it to anyone. Then the person whispers it, word for word, to another person. That person, in turn, whispers it to still another, and so on, through all the people playing the game. The last person writes down the message word for word as he or she hears it. Then the two written statements are compared.{#blank#}3{#/blank#}．

    {#blank#}4{#/blank#} The simple fact that people repeat a story in their own words changes the story. Then, too, most people listen imperfectly. And many enjoy adding their own creative touch to a story, trying to improve on it, stamping it with their own personal style. Yet those who hear it think they know.

    {#blank#}5{#/blank#} A statement of opinion by one writer may be restated as a fact by another, who may in turn be quoted by yet another; and this process may continue, unless it occurs to someone to question the facts on which the original writer based his opinion or to challenge the interpretation he placed upon those facts.

A. Typically, the original message has changed.

B. Finally everybody gets the meaning.

C. Unfortunately, passive learning has a serious problem.

D. Knowledge is passed down from generation to generation.

E. That's what happens in daily life.

F. This process is also found among scholars and authors.

G. We can achieve knowledge either actively or passively.

    Being physically active three times a week reduces the odds of being depressed by about 16%, according to new UCL research carried out as part of the Public Health Research Centre.

    The study, published in JAMA Psychiatry, found a two-way relationship between depression and physical activity. People who increased their weekly activity were reported to have fewer depressive symptoms but those with more depressive symptoms were less active, particularly at younger ages.

    Researchers followed 11,135 people born in 1958 up until the age of 50, recording depressive symptoms and levels of physical activity at regular intervals in adulthood. They found that each additional activity period per week reduced odds of depression by 6%. In England 19% of men and 26% of women are currently classed as "inactive", and this study suggests that activity could significantly improve their mental as well as physical health.

    "Assuming the association is causal, physical activity has a protective effect against depression. If an adult between his twenties and forties who isn't physically active became active 3 times per week, he would reduce his risks of depression by about 16%," said Dr Snehal of the UCL Institute of Child Health, lead author of the study.

    Professor Mark，Director of the Public Health Research Centre, said: "Many people are already aware of the benefits of physical activity on their general health, but now we are seeing more evidence that suggests it also has a positive effect on a person's mental well-being. The latest research highlights just how important it is to ensure that people are working and living in environments that allow them to be both physically active and mentally healthy."

    It's a real case of fish out of water. Blennies (鲇鱼) in the South Pacific Ocean are gradually relocating to land to escape their predators (捕食者), in an example of evolution in action.

    Fish first began crawling onto dry land about 400 million years ago, kicking off an evolutionary chain of events that led to humans. But their reasons for exiting the sea have been uncertain.

    To look for clues, Terry Ord at the University of New South Wales in Australia has been studying several species of blennies at Rarotonga, the largest of the Cook Islands.

    At low tide, blennies are commonly found swimming in rock pools around the edges of the island. But when high tide moves in, they climb up to dry land and move around the rocks until the tide retreats.

    The researchers found that this is most likely to avoid predators that swim in with the rising tide – mainly bigger fish like lionfish.

    To test what would happen if blennies did not have an escape plan, they made blenny models and sank them in the sea. The mimics ended up with wounds, bite marks and chunks-missing.

    Of course, there are still dangers for blennies on land, like the occasional bird attack, but the predation risk on land is a third that of underwater.

    What's more, moving onto land has additional benefits for blennies. Holes in the rocks provide sheltered nests for laying eggs, and they can maintain their diet of bacteria.

    In fact, several species of blenny fish at Rarotonga have already made the full transition to land-dwelling (陆生的) species. They continue to breathe with their gills, but have developed stronger tail fins and jump from rock to rock.

    Ord believes that many evolutionary processes have been driven by the need to escape predators. “It is often assumed that animals move homes to find new sources of food, but in many cases, escaping predators is a stronger motivation.” he says.

For most of us, walking is something we do automatically. It doesn't require much effort, so many of us fail to remember the benefits of walking for health.

Physical activity doesn't need to be hard. Whether you're regularly active or not, even a quick ten-minute daily walk can deliver a host of health benefits. But what happens if we stop walking ahead and start challenging our brains and bodies by walking backwards? Not only does this change of direction demand more of our attention, but it may also bring additional health benefits.

One of the most well-studied benefits of walking backwards is improving stability and balance. Walking backwards can improve how a person walks and balance for healthy adults and those with knee problems. Walking backwards causes us to take shorter, more frequent steps, leading to improve the muscles of the lower legs. But the benefits of changing direction aren't just that- -an interest in backwards movement has led researchers to discover various other benefits. While normal walking can help us maintain a healthy weight, walking backwards may be even more effective. Energy expenditure when walking backwards is almost 40 percent higher than walking at the same speed forwards, with one study showing reductions in body fat for women who completed a six-week backwards walk.

Walking backwards is simple, but that doesn't mean it's easy. So, how can you add walking backwards into your exercise plan? When walking backwards, we're more likely to crash into something or fall over, so in the interest of safety, it's best to start indoors where you won't crash into someone or outside in a flat, open area. Look over your shoulder. Keep your head and chest upright while reaching back with your big toe for each step, rolling through the foot from toe to heel. Once you become more confident walking backwards, you can begin to speed things up.