People can be addicted to different things, e.g. alcohol, drugs, certain foods, or even television. People who have such an addiction are compulsive, i.e they have a very powerful psychological need that they feel they must satisfy. According to psychologists, many people are compulsive spenders; they feel that they must spend money. This compulsion, like most others, is irrational-impossible to explain reasonably. For compulsive spenders who buy on credit, charge accounts are even more exciting than money. In other words, compulsive spenders feel that with credit, they can do anything. Their pleasure in spending enormous amounts is actually greater than the pleasures that they get from the things they buy.

    There is even a special psychology of bargain hunting. To save money, of course, most people look for sales, low prices, and discounts. Compulsive bargain hunters, however, often buy things that they don't need just because they are cheap. They want to believe that they are helping their budgets, but they are really playing an exciting game: when they can buy something for less than other people, they feel that they are winning. Most people, experts claim, have two reasons for their behavior: a good reason for the things that they do and the real reason.

    It is not only scientists, of course, who understand the psychology of spending habits, but also business people. Stores, companies and advertisers use psychology to increase business: they consider people's need for love, power, or influence, their basic values, their beliefs and opinions, and so on in their advertising and sales methods.

    Psychologists often use a method called “behavior therapy” to help individuals solve their personal problems. In the same was, they can help people who feel that they have problems with money.

    Each year, we are exposed to ten thousand ads on average. They try to sell us their products by using beautiful art, videos, images or slogans that are catchy. The most famous companies have highly popular logos that can be recognized by almost everybody. For those of you who have seen the movie Finding Forrester, there is that scene where Jamal walks up to some guy with a BMW and asks him what the car logo means. The man did not know the answer and since that day, whenever I see a famous company logo I try to find the meaning of it.

    Many think the horse on the Ferrari logo represents the horsepower of the cars they manufacture. The story behind it is far more interesting. During World War I, a pilot, Count Francesco Baracca, painted the horse on his airplane to bring him luck. He had it on his plane because it was the logo of his squadron（空军中队）. Baracca's mother then convinced Enzo Ferrari to put the logo on his racing cars in the early 1930's to bring good luck to the drivers. The logo then stayed the same ever since. The yellow on the background represents the birthplace of Enzo Ferrari.

    Starbucks started in 1971, in Seattle. The mermaid（美人鱼）represented on the logo is now known by any coffee drinker. It is a mythological sea creature with the look of a female, the only difference being that they have a tail of a fish. The reason why Starbucks incorporated one in their company logo is that it was believed that mermaids used to sing to sailors in order to make them walk away from their ship or to ground their ships. In the 1500s, spices, tea and coffee were popular merchandise to trade. So the mermaid in the logo of Starbucks is the one that "brings" coffee and tea to the stores.

    While we all try to find happiness, sometimes we still end up feeling low. While most people can control this feeling, low moods can stay with some, leading to depression. About 322 million people suffered from depression in 2015, according to a report by the World Health Organization in February. This is more than 4 percent of the world's population.

    Depression is described by the WHO as a mental disorder. It has several symptoms including sadness, loss of interest and feelings of low self-worth. In severe cases, depression may even lead to suicide.

    The number of people living with depression is increasing. The WHO reported a rise of 18.4 percent between 2005 and 2015. Young people are a group known to suffer with depression. “The pressures on today's youth are like no other generation, perhaps,” Dan Chisholm, an official of WHO, told Reuters.

    In China, depression among young people is on the rise, Zhu Zhuohong, a psychology professor with the Chinese Academy of Sciences, told Xinhua News Agency. Competition to outperform others, especially in education, can cause a lot of pressure for Chinese youth.

    Almost 1.2 million Chinese people aged 15 to 24 suffer from depression, according to a report released by British science journal The Lancet in May.

    Luckily, more and more efforts are being made to deal with this problem. This year's World Health Day, held on April 7, will focus on depression. The day will highlight (强调) the “Depression: let's talk” campaign. The campaign aims to make sure that people with depression both seek and get help.

    On a clear night, you can see a sky paced with stars. But you can't see planets orbiting any of these stars, even with the strongest Earth—based telescopes. Astronomers reported that they discovered seven Earth—sized planets orbiting a nearby star called TRAPPIST – 1 in February. They had to rely on indirect evidence to tell them that the planets are there. By doing some math, they figured out the number of planets and the distance of their orbits.

    TRAPPIST – 1 is a red dwarf （红矮星）, much smaller than our sun, but larger than Jupiter (木星). If the sun were the size of a basketball, TRAPPIST – 1would be the size of a gold ball. This star is one of our closest neighbors, just like the moon to the earth in space.

    When astronomers using Earth-based telescopes to study TRAPPIST – 1,they noticed that every once in a while, it became slightly dim（昏暗）. They decided that a planet must be passing in front of the star, blocking part of the light. This dimming would come and go as the planet orbited the star, passing alternately (交替地) behind and in front of the star regularly.

    By making careful observations, astronomers expected to get a rough idea of the planet's size from the pattern of dimming light. But the light level changed often and not at evenly spaced (均匀间隔的) times. The astronomers had to conclude they were looking at more than one planet! To get additional data, NASA's spritzer Space Telescope measured TRAPPIST –1's brightness nearly continuously for 20 days, catching 34 crossings of planets in front of the star. Sorting through the mess of data, the astronomers found that the innermost planet completes its orbit in 1.5 Earth days, while the outermost planet takes 20 days. Once you know how long it takes each planet to complete an orbit, you can work out how far it is from the star compared with the other planets.

    The TRAPPIST – 1 planets are not alone. So far, astronomers have found more than 3,400 planets that orbit other stars.

    Some young Cambodians are learning a new sport — skateboarding. The country's first skateboard park is located on the grounds of a local charity group at the edge of Phnom Penh, the capital.

    Sports like Khmer boxing and soccer are wildly popular in Cambodia. But Chea, who has been skating for 6 months, says skating has already become his favorite sport.

    The skaters are learning tricks like launching off a jump or half-pipe and flying through the air on their narrow wooden boards.

    A non-governmental organization called Skateistan Cambodia organizes weekly programs at the park. Skateistan started its work in Afghanistan years ago. Rory Burke is working with the group which expanded to Cambodia last year.

    Rory Burke points out, "Yeah, it's definitely not a typical Cambodian pastime (消遣). And I think the idea of 'why skateboarding is that it's not been done before here. We want to use skateboarding as something saying, 'Hey, this is new, this is something different. And that kind of itself becomes a little bit of hook. People see it and they think and they say, "Wow, 'what is that?', and they want to get involved. "

    Skateistan partners with local groups that work with young people. The park is on the grounds of the group known as PSE, where children attend school and learn a trade. There are almost one hundred twenty participants. They all come from troubled lives.

    Seventeen-year-old Sang Rotha is a student at PSE. "Sometimes I don't do well on subjects like math," he says, "I feel bad when I find it hard to keep up with my lessons. So that is why I skateboard—to improve my bad feelings. "

    He says he began skateboarding more than a year ago. Before he started training, it seemed very easy. But it was very difficult to learn tricks, and he got hurt a lot from falling off.

    Rory Burke says learning to deal with the difficulties is part of the lesson for these young skateboarders.

    Feeding birds is a popular way to watch wildlife. But experts say it might put wild birds at risk.

    Feeding birds is not necessary for their survival except in extreme weather conditions. Feeders(喂食器)can definitely help birds get through that kind of weather. But most birds eat insects and show little interest in bird feeders. For those birds, we can grow native plants in a natural environment. Birds which are fond of eating seeds will be more likely to come to feeders if there is some cover nearby. This lets them feed and then fly to protective areas, such as in trees.

    The most common mistake people make with their bird feeders is that they put feeders in places where birds are easily frightened by passers-by, risk being hurt by cats, or risk flying into windows.

    So set up a bird feeder at least one meter away from a window. That way, if a bird gets frightened, it won't get killed when it hits the glass. Owners of cats should keep them inside home so they can't hurt the birds.

    Some birds are more aggressive at feeders. They eat a lot and do not leave much food for other birds. A solution is to put the food in more than one place by using different kinds of seeds or fruits. This can also increase the number and diversity of birds in your neighborhood. But don't feed wild birds anything salty, like potato chips, or food that could choke them, like bread.

    Pay attention to food quality and freshness. Unprotected food left too long in feeders will turn moldy(发霉), which can kill wildlife.

    Another word of advice: Always provide a supply of clean water for birds, but use care when looking for the right birdbath. If the birdbaths are too deep for birds, putting a few large stones in the water can give the birds a place to sit.