World Book Day falls on April 23 every year．It was set up by the United Nations Educational,Scientific, and Cultural Organization(UNESCO) in 1995 to encourage people, especially teenagers, to discover the pleasure of reading．It is also the day to honor great writers，for example，William Shakespeare，born or dead on that day．

    Many countries celebrate World Book Day．Take UK as an example．On that day，millions of school children can buy books of special price，a much lower price than usual，in any bookstore．It has been done every year since 1998．World Book Day is also celebrated in China. Our Former Premier Wen Jiabao, a bookworm, who does lots of reading every day, has called on people to do more reading. He suggested that young people should spend more time reading．"Books cannot change the world, but people can change the world by changing themselves through reading,” he said．

    Why do people like reading? One big advantage is that reading helps us become more knowledgeable and more intelligent. Also, reading helps us to follow the latest developments of science and technology. Besides, reading gives us information about other cultures and places of the world. When we read, we may find many things that are unfamiliar to us. We would have to use our brain to think about them or do more reading to find out the answers. The more we read, the more we know. What's more, reading is also one of the most important ways to learn a foreign language like English．

    "Reading makes a full man" (Bacon，1597). Books，magazines，newspapers and other kinds of materials can help us to know more about the outside world and perfect us. So it is necessary for us to spend time on reading every day．

    Last month, the president of the Maldives, Mohamed Nasheed, held an underwater meeting. The purpose of the ocean floor conference is to highlight the effects of global warming on his island nation.

    The Maldives, located in the Indian Ocean, is the lowest-lying country on Earth. Melting glaciers and polar ice are causing sea levels to rise, putting the Maldives and other low-lying areas at risk of being swallowed by the sea within the next 100 years.

    What can be done? Scientists and leaders from 190 nations will try to figure that out at the United Nations climate change conference next month. The main goal of the meeting is to come up with a new climate agreement for 2012 and beyond. That is when the existing plan, the Kyoto Protocol will expire. The agreement was created in Kyoto, Japan, in 1997. Since then, it has been ratified(正式批准) by 190 nations. The countries promised to limit the amount of greenhouse gases, such as carbon dioxide, which they produced each year.

    The debate over who should cut greenhouse emissions has been going on for years. The US has been hesitant to reduce emissions unless fast-growing nations such as China and India also reduce their use of fossil fuels. In recent months, China has taken steps to be greener. But India has been unwilling to change. It argues that it is unfair for rich nations to ask poorer countries to cut down on emissions.

    While world leaders work on a plan in Copenhagen, there are many things you can do to help the planet. You can save fuel by walking or biking instead of riding in a car. You can start a recycling program in your community. You can plant trees. Trees absorb carbon dioxide from the air and give off oxygen.

    How could we possibly think that keeping animals in cages in unnatural environments -mostly for entertainment purposes - is fair and respectful? Zoo officials say they are concerned about animals. However, most zoos remain “collections” of interesting “things” rather than protective habitats.

    Zoos teach people that it is acceptable to keep animals bored, lonely, and far from their natural homes. Zoos claim to educate people and save endangered species, but visitors leave zoos without having learned anything meaningful about the animals' natural behavior, intelligence, or beauty. Zoos keep animals in small spaces or cages, and most signs only mention the species' name, diet, and natural range.

    The animals' normal behavior is seldom noticed because zoos don't usually take care of the animals' natural needs. The animals are kept together in small spaces, with no privacy and little opportunity for mental and physical exercise. This results in unusually and self-destructive behavior called zoochosis. A worldwide study of zoos found that zoochosis is common among animals kept in small spaces or cages. Another study showed that elephants spend 22 percent of their time making repeated head movements or biting cage bars, and bears spend 30 percent of their time walking back and forth, a sign of unhappiness and pain.

    Furthermore, most animals in zoos are not endangered. Captive breeding(圈养繁殖) of endangered big cats, Asian elephants, and other species has not resulted in their being sent back to the wild. Zoos talk a lot about their captive breeding programs because they do not want people to worry about a species dying out. In fact, baby animals also attract a lot of paying customers. Haven't we seen enough competitions to name baby animals?

    Actually, we will save endangered species only if we save their habitats and put an end to the reasons people kill them. Instead of supporting zoos, we should support groups that work to protect animals' natural habitats.

    We bet that on cold winter days, many of you love to stay in your warm home and, every now and then, come out into the kitchen for a snack. Unfortunately, plenty of small insects like to do the same thing! Winter is the time when small insects enter your house without an invitation. The season can be difficult for such creatures. In winter the air is cold, the ground is hard and many trees have no leaves. So small insects do what they have to do to survive.

    Monarch butterflies head south to warmer climates. Ants crowd in deep underground colonies and eat food they have been storing all year. Many insects go into a deep sleep called diapauses. There're different kinds of diapauses, but all are similar to hibernation, a time when bigger animals become inactive in the cold. Insects go into an inactive period, too, but it often isn't when the temperature drops.

    They rely on more dependable signals in the environment. For example, many insects can tell how much sunlight there's each day. They use that to tell themselves when to shut down. Insects are cold-blooded, meaning that their inside temperature is the same as the outside. They can't move much when it gets below 40 degrees Fahrenheit. So they search for any warm place.

    They're looking for protection. These guys have been doing this for 300 million years, so they don't really know they're coming into your house. The home is a recent event in terms of their evolutionary (进化的) behavior. They enter through tiny cracks or come in unnoticed on your clothes or shoes. Remember that they may be entering your homes for warmth and food, but they don't care about humans.

    Alzheimer's disease is a major national health problem. Nearly 2 million Americans over the age of 65 have Alzheimer's disease. It is a leading cause of death among the elderly. But Alzheimer's disease is not confined (限于) to the aged. There may be a million or more people under the age of 65 suffering from the disease.

    At one time, people suffering from the disease were said to be "getting old". The disease was thought to be a natural part of growing old, but it is now known that Alzheimer's disease strikes young and old alike. It is an organic (器官的) disease, that destroys brain cells.

    Alzheimer's disease affects the patient's memory, speech, and movement. In the beginning stages of the disease, the patient may seem slightly confused. He may have trouble speaking, and then the patient's memory begins to fail. He may forget dates, numbers, names and plans.

    As the disease progresses, the patient may not recognize family and friends. These symptoms(症状) often cause terrible anxiety in the patient. He may feel lost and frightened. Sometimes the patient reacts with wild and bad behavior.

In the last stages of the disease, the patient may not be able to take care of himself. He may have lost the ability to speak and walk.

    Scientists don't know exactly what causes Alzheimer's disease. It may be caused by a virus (病毒). It may be caused by a poisonous substance(物质) in the environment. At present, there is no cure for the disease. But there are ways to slow its progress. Exercise and physical treatment can help the patients of this disease.

    It was an autumn day, and 1 was standing in the kitchen, hanging my head over the counter and trying to figure out how many calories were in a bowl of homemade yogurt and fruit. And I felt annoyed.

    I was 16, and my best friend and I had gone to our first Weight Watchers meeting. It was the trend in the mid-1980s, and even though I was an athlete, like many teen girls, I didn't necessarily like what I saw in the mirror. But after a week or so of recording every meal and snack and calculating the calories, I had had enough. I went back to my routine of chowing whatever I wanted, running and skiing, and let that be that. And it's still pretty much what I do; as long as the workouts are regular and the food is whole and balanced, my body's set point hasn't varied for years.

    The weight loss trend of three decades ago−full of scales and counting calories−has fallen away. Now fasting is popular. The ways to keep fit vary: on the 5:2 diet a person eats for five days and fasts for two days each week, while the 18:6 refers 10 fasting for 18 hours and then eating within a six-hour window each day.

    In this issue, Associate Editor Mark Barna tries to understand the science behind the fasting plans. Researchers have found that animals like monkeys age more slowly after years of eating less, and in the lab in humans, they saw improvements in a number of signs that indicate risk of some hard to cure diseases. The hope for healthy weight loss isn't over yet, but at least now the calculators don't have to be out at every meal.