We often find that weekends and holidays feel so short while classes and work feel so long. Actually, though, we know that this is not true. But we still wonder where that strange feeling comes from.

    In fact, this is one of the ways that we're tricked by time, according to the website. All that S interesting. The website lists several wrong impressions (印象) we often have about time. Let's have a look.

    First of all, emotions affect (影响) our time-keeping abilities. Negative emotions (消极情绪). especially anxiety and boredom, make time seem longer because they make us concentrate (集中) more on the passage of time. However, when we are enjoying ourselves, we pay more attention to what we are doing and are likely to lose track of (失去对……的意识) time.

    Here is another example. In 2007, a group of scientists carried out a test. In the test, people fell 50 meters into a safety net and were then asked about their experience. Although the experience took shorter than 3 seconds, the people thought it was much longer than it actually was.

    This is because of the way our bodies reply to danger, according to the scientists. Our bodies produce a chemical called adrenaline (肾上腺素) when we are faced with danger. It allows us to concentrate better so that we can stay alive. As a result, we are able to remember far more details (细节) over a short period of time, which makes it seem like time is going more slowly.

    Another situation when we make mistakes about time is when we take afternoon naps (午觉). Have you ever had trouble telling what time it is after a long nap? That's because the best amount of time for a nap is 20 minutes. After 20 minutes, you enter a new stage of sleep called slow-wave sleep. If you wake up mid-way in this stage, it will take a while before you can correctly perceive (感知) time again.

    Yes, time can be mysterious (神秘的) and there is no way to control it. So, perhaps the best thing to do is to make good use of every minute.

    Giraffes are beautiful, smart and friendly. They have long legs and necks (脖子). They are so tall that they can grow up over 5 meters (米). So how do they sleep or drink?

    You may think it's difficult for them to sleep, but they have no such problems because giraffes don't often stop for a sleep. Giraffes just need to sleep about thirty minutes a day. When they sleep, they don't always lie down (躺下). They usually sleep for minutes at a time, because it's difficult for them to get up again. And it's a great danger to sleep in the wild (荒野). But the giraffes in the zoo sleep for about 4-6 hours every day. They usually lie down when they sleep.

    Drinking water is a big problem for giraffes because their long necks are too "short". To drink water, they must spread (伸展) their front legs in a difficult way. And in this way, other animals like Africa's big cats can easily hunt (猎食) them. So they usually get most of their water from the trees and flowers. Giraffes don't need to drink water very often. They can even drink no water for months!

    Maybe a lot of thin people will be worried about their health if the inside fat matters.

    Some doctors now think that the inside fat around important organs like the heart or liver could be as dangerous as the outside fat which can be noticed more easily.

    "Being thin doesn't surely mean you are not fat," said Dr Jimmy Bell at Imperial College. Since 1994, Bell and his team have tested nearly 800 people with MRI to create "fat maps" showing where people store fat.

    According to the result, people who keep their weight through the food they usually eat rather than exercise are likely to have major deposits (堆积物) of inside fat, even if they are thin.

    Even people with normal Body Mass Index (体重指数) scores can have surprising levels of fat deposits inside. Of the women, as many as 45 per cent of those with normal BMI scores (20 to 25) actually had too high levels of inside fat. Men were nearly 60 per cent.

    According to Bell, people who are fat on the inside are actually on the edge of being fat. They eat too many fatty and sugary foods, but they are not eating enough to be fat. Scientists believe we naturally store fat around the stomach first, but at some point, the body may start storing it elsewhere.

    Doctors are unsure about the exact dangers of inside fat, but some think it has something to do with heart disease and diabetes (糖尿病). They want to prove that inside fat does harm to the body's communication systems.

    The good news is that inside fat can be easily burned off through exercise or even by improving your eating habits. "If you want to be healthy, there is no other way. Exercise has to be an important part of your lifestyle," Bell said.

Every year，Time magazine puts out its list of the year's best inventions.Some of them help us solve problems，while others make life easier or more fun.Here are three of the inventions on this year's list.Which one do you think is the best？

Life﹣like animals

At the Hologram Zoo（全息动物园） in Australia，you don't just see a giraffe.You see a group of giraffes running towards you and then over you."We show people things they have never seen before，"says the zoo's CEO.Visitors to the zoo can see life-like wonders.Thanks to hologram technology，the public can see wildlife while no animals have to be kept in cages.

Stopping fires

Alert California is a safety program in California.It uses AI to predict wildfires.The AI detector（探测器） uses more than a thousand cameras in forests across the state.It can spot smoke and other early signs of fire.In two months，the program correctly predicted 77 fires before any 911 calls came in.

Air on Mars

If astronauts land on Mars in the future，they'll need air to breathe and a way to get home.NASA's Moxie can help solve both problems.This small equipment can separate oxygen（氧气） from the atmosphere（大气） on Mars and help astronauts breathe.In addition，the oxygen can be used to provide energy for spaceships.This is important for sending astronauts home from Mars.

①As missing children get older，they become quite different from the faces in their last﹣known photographs，which makes finding the really difficult. Now AI（人工智能）can make it easier to match any found children to those old photos. 

②Police can use software（软件）to age photos of missing people，but it seems to work best in adults

③Unlike adults ，the faces of children change greatly as time goes by，and matching photos of found children to old images（画像）（数据库）of missing children is difficult. "Even with a recent face image of a child，it is quite hard for a human to recognize（辨认），who the child is from a large data set of child face images，" says Debayan Deb at Michigan State University. 

④Now Deb and his teammates have created an algorithm（算法）to work out the problem. They created a face﹣recognition algorithm on data sets，which have images of nearly 1

⑤AI learned to match recent photographs of children with images taken 2. 5 years earlier. The correct matching rate can be 80 percent. With one year between the two photographs，it was 90 percent correct at recognizing faces. This dropped to 73 percent after three years. The new AI might help to improve accuracy （准确性）of this kind of software

⑥Deb's next goal（目标 ）is to make the age gap wider. His team also hopes to develop an app to fight against the sale of children.