【推荐3】Too many people want others to be their friends, but they don’t give friendship back. That is why some friendships don’t last very long. To have a friend, you must learn to treat your friend the way you want your friend to treat you. Learning to be a good friend means learning three rules: be honest(诚实的);be generous(宽宏大量的);be understanding.

Honesty is where a good friendship starts. Friends must be able to trust(信任) one another. If you don’t tell the truth, people usually find out. If a friend finds out that you haven’t been honest, you may lose your friend’s trust. Good friends always count on one another to speak and act honestly.

Generosity means sharing and sharing makes a friendship grow. You don’t have to give your lunch money or your clothes, or enjoyments, like your hobbies and your interests. Naturally you will want to share your ideas and feelings. These can be very valuable to a friend. They tell your friend what is important to you. By sharing them, you help your friend know you better.

Sooner or later everyone needs understanding and help with a problem. Something may go wrong at school. Talking about the problem can make it easier to solve. Turning to a friend can be a first step in solving the problem. So to be a friend you must listen and understand. You must try to put yourself in your friend’s place so you can understand the problem better.

No two friendships are ever exactly alike (相同). But all true friendships have three things in common. If you plan to keep your friendships, you must practice honesty, generosity and understanding.

【推荐1】Christian Eijkman，a Dutch doctor，left the Netherlands for the island of Java. Many people on the island had a disease called beri-beri. He was going there to try and find a cure.

At first，Eijkman thought some kind of germ（细菌）caused beri-beri. He raised some chickens. He didn't eat them，but made experiments on them. The local people were quite surprised at that. One day he noticed that his chickens became sick when they were fed the food most Javanese ate refined white rice（精炼米）. When he fed them with unrefined rice，also known as brown rice，they recovered. Eijkman realized that he had made an important discovery—that some things in food could prevent disease. These things were named vitamins（维生素）. The Javanese were not getting enough vitamins because they had actually removed the part that contains vitamins. Later，other diseases were also found to be caused by the lack of vitamins in a person’s food.

Today many people know the importance of vitamins and they make sure they have enough vitamins from the food they eat. If they don’t，they can also take vitamin pills.

【推荐2】I have beard that it takes many more muscles to frown（皱眉头）than to smile. Is it true，and does that mean that smiling is easier?

Phil Discarson, Preston, England

I read on a website (www.straightdope.com) that the opposite is true. According to someone called Doctor Song, a plastic surgeon, you use 12 main muscles for a genuine smile, but only 11 for a frown. But he says that even though we use more muscles to smile, ifs actually easier because, since we smile more often than we frown, our smiling muscles are in better condition.

Carl Preston, San Francisco, USA

It depends what you mean by smiling. Remember that line from Shakespeare, “a man may smile and smile and be a villain' —I think it^ from his play Hamlet. Anyone can look as if they are smiling by using the zygomaticus major and minor (they pull up the comers of the mouth), the levator labii super ions (which pull up the mouth and the comers of the nose) and the risorius (which pulls the comer of the mouth to one side). But that's not a real smile. A real smile uses the orbicularis oculi, which encircle each eye, and so when you smile like this, these muscles tighten the skin round the eye to give that ‘crinkling’ effect which creates ‘laughter’ lines. That’s a REAL smile!

Sarah Green (Dr), Birmingham, UK

Counting the muscles，it takes to smile and frown isn’t the issue，for me. I am more interested in the fact that you can find examples of the saying that ‘it takes less effort to smile than to frown’ as far back as the 19th century. That’s because it’s a piece of advice, not a scientific fact. ‘Smile, and the world smiles with you? is another saying like that. Others say that if you smile, you will almost always feel happier. So which comes first, the smile or the happiness?

Well I just read some research, which said that when we smile (or frown), our bodies get the message, even if we are only pretending. Apparently, they got some people to pretend to be angry, sad, sick, etc., and use the appropriate facial expressions, and measured what happened to their bodies. And the unbelievable thing was that even though the test subjects knew they were acting, their bodies didn't. Their heart rates increased, their skin temperature got hotter and there were signs of sweating—all physical signals of real anger, etc.

Felicity Poole, Amsterdam, Holland

【推荐3】Most birds, in particular, exhibit some degree of patterns and colours. Australia’s zebra finch (斑胸草雀), for example, was so named because of the zebra-like black and white bars on its tail. But it also has many other colours and patterns, from a bright orange bill to fine white spots along its reddish-brown sides. It’s not uncommon to spot the bird in the drier parts of Australia.

We tend to suppose all individuals of that species have their spots and bars in the same places. Look closer yet we’ll see that the quantity and design of these patterns vary between individuals. And somehow a bird exhibits a more obvious feather variation. Occasionally, we see one that has larger than usual pale areas of feathers or, more rarely, has lost its normal patterning altogether.

Colouration and patterning in all animals are caused by a range of pigments (色素). Melanin (黑色素) is responsible for blacks and browns, and a lack of this pigment can cause a partial or total loss of an individual’s dark patterning. The two main terms that describe these abnormalities are albinism and leucism. Both conditions are genetic and both can lead to a very similar physical appearance. Leucism, however, causes a lack of the pigment cells that produce melanin. But albinism causes the production of melanin to be reduced or absent.

Can we distinguish between the two conditions without the help of a cellular biologist? Yes. Albino animals have fully unpigmented red eyes. Leucistic animals, on the other hand, never completely lose pigment from the eye, although they can have blue eyes due to a partial loss of pigment.

Why don’t we see more albino or leucistic birds? Because the lack of melanin reduces the strength and lastingness of the affected birds’ feathers, making them more easily broken. Additionally, the birds’ vision and hearing are negatively affected, making them less able to hunt. The brighter feathers and lack of patterning also make them easier for attackers to see.

【推荐1】Fish cats are a kind of cats that love water and love to fish. They are like tigers and lions, only much smaller, around twice the size of our average pet cats. They live in wetlands of South Asia and mangrove forests(红树林)of South and Southeast Asia. Like many endangered species, fish cats were in danger of dying out more than twenty years ago, mainly because of the great international need for fish food and the people s cutting of the mangroves at an extremely fast speed.

Mangroves of Southeast Asia are home to a great many fantastic species, like fish cats, turtles, shorebirds and others. Mangroves can protect soil, and they can be the first line of protection between storms, tsunamis and the millions of people who live next to them. The fact is that mangroves can store almost five to ten times more CO₂ than other forests. So protecting mangroves may well be like protecting five to ten times more of other forests.

Ten years ago, in South India, many people came together to change the future of their home. In less than 10 years, with international support, the state forest departments and the local people worked together to restore over 20,000 acres of unproductive fish and shrimp farms back into mangroves. Now experts are working with them in helping study and protecting the mangroves as well as the species living in them. Fish and shrimp farmers are now willing to work with experts to test the harvest of nature protection like fishes, turtles and other species in mangroves. The local farmers are encouraged to protect and plant mangroves where they have been lost. A win win-win for fish cats, local people and the global ecosystem(生态系统)is being built.

【推荐2】Can you be too beautiful? It is hardly a problem that most of us have to bother — as much as we might like to dream that it were the case.

Yet the blessings and curses of beauty have been a long-standing interest in psychology. Do those blessed with shiny faces and an attractive body live in a cloud of appreciation — or does it sometimes pay to be ordinary? At the most basic level, beauty might be thought to carry a kind of halo (光环) around it; we see that someone has one good quality, and by association, our deep mind may assume that they have other good ones too.

But if beauty pays in most circumstances, there are still situations where it can have opposite results. While attractive men may be considered better leaders, for instance, hidden sexist prejudices (偏见) can work against attractive women, making them less likely to be hired for high-level jobs that require power. And as you might expect, good-looking people of both sexes run into envy — one study found that if you are interviewed by someone of the same sex, they may be less likely to employ you if they judge that you are more attractive than they are.

More worryingly, being beautiful or handsome could harm your medical care. We tend to link good looks to health, meaning that illnesses are often taken less seriously when they affect the good-looking. When treating people for pain, for instance, doctors tend to take less care over the more attractive people.

To conclude, scientists point out that focusing too much on your appearance can itself be harmful if it creates stress and anxiety — even for those already blessed with good looks. “If you are crazy about attractiveness, it may affect your experience and interactions,” she says. It’s an outdated saying, but no amount of beauty can make up for a bad personality. As the writer Dorothy Parker put it so elegantly: “Beauty is only skin deep, but ugly goes clean to the bone.”