1 . Many people dream of traveling into outer space. However, spending too much time in space may cause health problems. That’s why astronauts shouldn’t spend more than six months on the International Space Station (ISS) at a time.

Muscle (肌肉) and bone loss(骨质损失). In a weightless environment, astronauts don’t need to use their muscles to support themselves. So their muscles start shrinking (萎缩). To keep their muscles strong, astronauts need to exercise for about two hours each day on the ISS.

Sleep disorder (紊乱). In space, the sun rises every 90 minutes. It is hard for astronauts to get used to this light-dark cycle (循环) when they sleep. Also, they need to sleep in a sleeping bag that is fixed to a wall. It is uncomfortable. Now astronauts have individual (单独的) sleeping pods (睡眠舱) that help shut out some of the light. Still, studies have found that most astronauts only sleep about six hours each night, even though they should have eight and a half hours.

Brain changes. Scientists have found that the position of the brain changes during spaceflight. This can influence how the brain deals with how we see, stay balanced (平衡) and move around. That’s why some astronauts can’t control their movement and balance after returning to Earth. Scientists have also found that astronauts may get used to this change after going on more spaceflights. But they still need to do more research.

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2 . CHOKING FIRST AID

3 . Because of COVID-19, people may have bad feelings, such as sadness, anxiety and fear. Helping yourself and your family members keep a positive attitude will be very important. Below are four ways to keep your body and mind strong.

When you stay at home for a long time, it is normal to feel upset or anxious. The first step is to recognize and accept these feelings. It means being honest about your feelings. Don’t hide your feelings. Accepting your feelings can actually help you manage them.

Keep a balanced diet and follow a daily routine (惯例). People who stay at home for a long time may easily have their routine turned upside down. Some people may stay up late at night and fail to get up during the day. Sleep is important for your personal health. Good sleep, especially deep sleep, can reduce anxiety.

Physical exercise is also an effective way to reduce anxiety. Even a small amount of physical exercise can immediately make you feel better. And it works for people of all ages. At this time, you probably could not do outdoor exercise. But you should still do some exercise at home. If you need exercise tips, try downloading an app or find them online.

Humans are social animals. If our need to socialize (社交) is not met, it may lead to bad feelings. Luckily, it is easy to connect with relatives and friends. Call someone or send a message on WeChat.

6 . Have you ever heard of the Eternal Flame Falls (永恒火焰瀑布)? It’s one of the most special waterfalls on our planet.

The waterfall is in a park in western New York, the USA. As we come close to it, we will smell something like bad eggs. That’s the smell of natural methane gas (沼气) produced by ancient rocks that are awfully hot. At the heart of the waterfall is a small flame.

The burning flame has been there for a long time. The locals believe it was created by elves (精灵). According to them, we may come across one while looking at the flame if we are lucky enough.

Another popular idea about the flame is that it’s alive because of the natural gas. It is widely believed that it was first set on fire a hundred years ago. Although the flame once went out, it was lit again right away.

However, Indiana University researchers think differently. The temperature of the flame is much higher than the boiling point of water, but their study shows that those rocks are not hot enough to lead to such a result. This means something else keeps the flame alive. However, the researchers are unable to discover the real reason behind it.

Arndt Schimmelmann from the university further explains that this special place has a different way to produce gas. “If there is another way of producing gas, there might be more gas sources (来源) than expected,” he adds.

7 . A thoughtful present shows the receivers that you care for them and makes them feel your love. But it isn’t easy to choose a thoughtful present. Here is some advice that may help you.

Care

There are many things you can buy for your friends, family members or even teachers. Each present sends a powerful message. And the closer your relationship is, the prettier your present can be. Before you buy something, consider the taste of the person you’re buying the present for. It’s not the price of the present, but the thought behind it.

Time

You can also give your time in many ways. A homemade present is special and shows you care enough to make an effort. It could be knitting (针织) a scarf, making a greeting card or baking (烤) lovely cupcakes. Whatever you decide, make it amazing—for them and for you.

Meaning

From “I’m sorry” to “I love you” and “thank you” to “good luck”, presents can express inner (内心的) feelings when you are too shy to speak them out. It’s also a wonderful feeling for you when the person is surprised and touched by your care and attention.

8 . There is an interesting part of your body. It is always dying, and it is replaced(更新) every 28 days. Everywhere you go, you leave very small pieces of it. It is the largest part of your body. It is your skin(皮肤)

When we think of parts of the human body, we usually think of the heart or the brain. But the skin is also a part of your body. In fact, it makes up about 15% of your body weight and covers an area of about two square meters.

The skin is always replacing itself. Dead skin cells (细胞) are always falling off your body. In fact, scientists say that half of the dirt in your house is made up of dead skin.

The skin protects your body. Your skin is a covering for the inside parts. It also works hard to keep your body warm or cool. Very small holes in the skin can open or close to help control body heat.

Your skin is also a “feeler” for your body. It feels touch or pain. Parts of cells that feel touch are connected to the brain. When you touch something, your brain decides what to do and then tells your muscles(肌肉). But the parts that feel pain are connected straight to muscles. The muscles don’t need the brain to tell them to jump. Because of all the things the skin does, it truly is an amazing part of your body.

10 . Electric cars may seem like a recent invention, but they’ve been around for years. In the early 1900s, there were more electric cars on the road than there were petrol（汽油）cars. At that time, petrol was expensive compared with other fuels（燃料）. When petrol prices dropped and new technologies were developed, electric cars went out of fashion. Instead, petrol cars became more popular because they could travel longer distances without stopping.

During the 20th century, petrol cars got bigger, heavier and faster. They needed more fuel, and it caused more air pollution. For years, car makers didn’t worry about pollution. They didn’t worry about the amount of petrol cars’ use, either. But when people began to realize that there was not enough oil on the earth, they asked car makers to produce more efficient（高效能的）and less polluting cars.

One method of solving the problem was a “hybrid” car（混合动力车）, one that ran partly on petrol and partly on electricity. Hybrid cars became popular in the 2000s when petrol prices went up and the prices of hybrid cars went down.

An all-electric car uses no petrol. The problem, however, is that car batteries（电池）need to be recharged（再充电）. That makes electric cars not so useful for long journeys.

Many people are not pleased with it. The government and car makers are working together to develop safe, cheap and useful electric cars. When people have these cars in the future, a petrol station may be a thing of the past.