Try this: For an entire day, forget about the clock. Eat when you're hungry and sleep when you're tired. What do you think will happen?

    You may be surprised to find that your day is much like most other days. You'll probably get hungry when you normally eat and tired when you normally sleep. Even though you don't know what time it is, your body does.

    These patterns of daily life are called circadian rhythms, and they are more than just habits. Inside our bodies are several clocklike systems that follow a roughly 24-hour cycle. Throughout the day and night, our internal clocks direct changes in temperature, body chemicals, hunger, sleepiness and more.

    Everyone's rhythms are unique, which is why you might like to stay up late while your sister always wants to go to bed early. But overall, everyone is programmed to feel tired at night and energetic during the day.

    Scientists have known for a long time that the light of day and the dark of night play important roles in setting our internal（内部的） clocks. Now, new discoveries are giving scientists insights into how these clocks work.

    Learning about our body clocks may help scientists understand why problems arise when we act out of step with our circadian rhythms. For example, traveling across time zones can make people wake up in the middle of the night. Regularly staying up late can make kids do worse on tests and quizzes. And working shifts at night leads to higher rates of heart disease, diabetes and obesity.

    “There is a growing sense that when we eat and when we sleep are important parts of how healthy we are,” says Steven Shea, Director of the Sleep Disorders Research Program at Brigham and Women's Hospital in Boston.

    Scientists still aren't sure why the timing of sleep matters so much, Shea says. But research findings suggest that our circadian rhythms are more important than we give them credit for.

    “During the night, we are prepared to sleep,” Shea says. “During the day, we are prepared to eat and move around. If you reverse (颠倒)what you are doing, everything is out of phase. That can have unfavorable consequences.”

    Art is considered by many people to be no more than a decorative means of giving pleasure. This is not always the case, however, at times, art may be seen to have a purely functional side as well. Such could be said of the sandpaintings of the Navaho Indians of the American Southwest; these have a medicinal as well as an artistic purpose.

    According to Navaho traditions, one who suffers from either a mental or a physical illness has in some way disturbed or get in touch with the supernatural—perhaps a certain animal, a ghost, or the dead. To break away from this, the ill person or one of his relatives will employ a medical man called a "singer" to perform a curing ceremony which will attract a powerful supernatural being. During the ceremony, which may last from 2 to 9 days, the "singer" will produce a sandpainting on the floor. On the last day of the ceremony, the patient will sit on this sandpainting and the "singer" will rub the sick or injured parts of the patient's body with sand from a specific figure in the sandpainting. In this way the patient absorbs the power of that particular supernatural being and becomes strong. After the ceremony, the sandpainting is destroyed so its power won't harm anyone.

    The art of sandpainting is handed down from old "singers". The materials used are easily found where the Navaho settle: brown, red, yellow, and white sandstone, which is ground（研磨）much as corn is made into flour. The "singer" holds a small amount of this sand in his hand and lets it flow between his fingers onto a clean, flat surface on the floor, with a steady hand and great patience. He is thus able to create designs of stylized people, snakes and other creatures that have power in the Navaho belief system. The traditional Navaho doesn't allow copying sandpaintings, since he believes the supernatural powers that taught him the craft have forbidden this; however, such reproductions can in fact be purchased today in tourist shops in Arizona and New Mexico. These are done by either Navaho Indians or by other people who wish to preserve this craft.

    All over the world people enjoy sports. Sports help to keep people healthy and happy, and to live longer.

    Many people like to watch others play games. They buy tickets or turn on their TVs to watch the games. Often they get very excited when "their" player or team wins.

    Some sports are so interesting that people everywhere go in for(参加) them. Football, for example, has spread(展开)around the world. Swimming is popular in all countries near the sea or in those with many rivers. What fun it is to jump into a pool or lake, whether in China, Egypt or Italy! And think of people in cold countries. Think how many love to skate or ski (滑雪) in Japan, Norway or Canada.

    Some sports or games go back thousands of years, like running or jumping. Chinese wushu, for example, has a very long history. But basketball and volleyball are rather new. Neither one is a hundred years old yet. People are inventing new sports or games all the time. Water-skiing is one of the newest in the family of sports.

    People from different countries may not be able to understand each other, but after a game together they often become good friends. Sports help to train(培养,训练) a person's character(性格,品格). One learns to fight hard but fight fair, to win without pride and to lose with grace(胜不骄，败不馁).

    Idioms are one of the hardest parts of learning a language. For those of you who don't know, an idiom is a phrase which has a meaning, but the meaning is not clear from the words themselves. If you translate an idiom word for word, it sometimes makes no sense at all. They are like puzzles and even native speakers can get confused when someone uses a phrase that they've never heard of.

With that in mind, here are five common English idioms that you can use in a variety of Situations.

⒈Get your act together (Meaning: you need to improve your behaviour/work)

    This might be something your teacher says to you if you score badly in an exam or if you misbehave in class. You can also use it to talk about people in general. For example, if your friend is being mean or nasty for no reason, then you can tell them that they need to get their act together.

⒉Pull yourself together (Meaning: calm down)

    This is a somewhat impolite way of telling someone that they are overreacting and that they need to relax. Only use this if you think the person you are speaking to is getting upset over something insignificant. If your friend tells you that their close relative has died, it is NOT the time to tell them to pull themselves together.

⒊I'm feeling under the weather (Meaning: I'm sick)

    Yes, it's longer and more difficult to say than 'I'm sick', but if your English teacher asks you why you haven't done your homework, he or she is more likely to forgive you if you say that you were feeling under the weather. You may not have done your English homework, but your teacher might be impressed that you know how to make eloquent excuses in a foreign language.

⒋It's a piece of cake (Meaning: it's easy)

    I don't know why this means what it does, but sometimes you just have to accept that English people use weird phrases.

⒌Break a leg (Meaning: good luck!)

    This is perhaps one of the most confusing yet well-known English idioms. If someone says this to you, do not take offence or think they are threatening you; they are just wishing you luck. It is most often used for people wishing success to actors and actresses before they perform on the stage, but it can be said in other situations, too.

    All in all, learning a new language can be challenging. It's definitely not a piece of cake, especially when there are so many confusing idioms. However, with enough hard work and interest, you will succeed in no time. Break a leg!

With all the dietary information online, it can be hard to know what tips to follow. Watch out for these words and expressions.

Fat Is Good

It doesn't matter if you are part of the fat is GOOD for you or BAD for you group, the important question to ask is the source of the fat. If it comes from a land-based animal, and is likely to be solid at room temperature, then it is saturated （饱和的） fat whereas if it comes from fish or plants, and it is likely to be liquid at room temperature, then it is unsaturated fat. All the evidence indicates that eating more unsaturated fat than saturated fat lowers your risk of dying early.

Natural Sugar Is Better

The vast majority of sugar we consume is sucrose （蔗糖）. It is the white powdered stuff we cook with and is made up of glucose and fructose. How about sugar from honey? It is often marketed as natural and better for you. Actually, it just has its own distinct flavour, but is as sweet because of glucose and fructose.

High-pH Water

Some people think we need to eat alkali （碱） food to maintain our blood at a pH of 7.4. But everything we eat or drink passes through the stomach, which, at a pH of 1.5, is the most acidic part of the body. It is then neutralised to a pH of 7. So, nothing we eat will change the pH of our blood.

Don't Eat Anything That You Can't Pronounce

Whether foods are natural or highly processed, they are all full of chemicals. Are you supposed to fear "phenylthiocarbamide", because you can't pronounce it? This is simply the chemical responsible for the bitter taste found in brassicas, the plants in the cabbage and mustard family.

Don't Eat Food With More Than Five Ingredients（佐料）

Simple foods are not necessarily healthier for you. If I, for instance, use Chinese five spice powder in a recipe, that would count as one of the five ingredients. However, what if I added the typical components of five spice powder separately into a dish? Does that mean my recipe suddenly becomes bad because it has more than five ingredients?