1 . If you feel stressed at school, what can you do to make yourself happier? Some may eat their favorite food or listen to some music. Others may go for a walk or get some exercise. A new study found another great way to lower students’ stress — playing with dogs.

Scientists studied 105 students between the ages of eight and nine. 35 trained dogs and their trainers also took part in the test. The children were divided into 3 groups. The students in the first group spent 20 minutes with a dog and its trainer. They watched the trained dogs perform and even played with them. They did this twice a week for 4 weeks. The second group spent the same amount of time doing exercise to relax. The last group did neither of these things.

During this time, the scientists recorded the students’ cortisol levels (皮质醇水平). Cortisol is a stress hormone (激素). The more stressed you feel, the more cortisol you will have in your body. What did the scientists find? Both the second and third groups showed rises in cortisol levels. The first group, however, showed no big increase. And the children in this group had the lowest cortisol levels right after playing with the dogs.

According to the study, students enjoy playing with dogs, and it helps them become happier. The stress hormone falls over time this way, which is good for students’ health. But here comes the next question: Is 20 minutes of playtime with a dog the best amount of time? Scientists are going to keep working to find out the answer.

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2 . ① Man has known more and more about space today. Space is not only wonderful but also dangerous. While working in space, astronauts are facing danger.

② Scientists have found out that radiation (辐射) is the greatest danger to astronauts in space. When astronauts are working in space, they are in danger of radiation from the sun and other stars, which is bad for their health. The damage of radiation is difficult to discover until their children or even grandchildren are born. Some special medicine may work a little, but there isn’t really helpful medicine.

③ Space rubbish is also a great danger to astronauts. There are 9000 man-made (人造) things flying in space. About 30% of these are man-made satellites (卫星), 10% are spaceships, and others are space rubbish. Even a small piece of these knocked against a spaceship window and did some damage. Scientists are watching and telling any possible danger all the time. They are working on helpful ways to do with space rubbish.

④ Although space is really dangerous, everyone on the earth is interested in it. In the near future, it may become usual for people to spend a few days in a space hotel. We may even choose to leave the earth and live in space for a few years. So we should care for space and do something to help improve the space environment.

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3 . Beauty sleep is a real thing. Researchers have shown that people who have enough sleep look more attractive(有魅力的) to others.

A few bad nights are enough to make a person look “especially” uglier, their sleep experiments show.

The researchers asked 25 university students to join in their sleep experiment. They were asked to get a good night’s sleep for two nights.

A week later, they were asked to sleep for only four hours every night for two nights. After both the good and the bad sleep, the volunteers were taken photos without make-up(化妆) by the researchers.

Next, they asked 122 strangers to have a look at the photos and judge(评价) them on attractiveness, health, and sleepiness, as well as asking them, “How much would you like to make friends with this person in the picture?”

The strangers were good at judging if the person they were looking at was tired, and, if they were sleepy, their attractiveness score was low.

The strangers also said they wouldn’t want to socialize with the tired students. The researchers say this is natural for people. An unhealthy-looking face makes people run away. In other words, people don’t want to be friends with the people that might be ill.

Dr. Brewer said. “Judgement of attractiveness is often unconscious(无意识的), but we all do it. and we are able to judge on even something small like whether someone looks tired or unhealthy. This study is a good reminder(提示) of how important sleep is to us.”

5 . Many cats like empty shoe boxes or packing boxes. When there are such boxes in the home, they often become the cats’ favourite places to be. And my cat, Molly likes staying in them too. I bought her an expensive cat house, but she still prefers to stay in an old box. Why is this? What’s so special about this box?

In fact, cats love boxes of all shapes and sizes better. Honestly, you should have a try. Just drop a box in front of them. The next thing you will see is real happiness on your cat’s face. One reason is that cats are born to be predators (捕食者). This is why they prefer to be covered on all sides. This helps them to hide themselves to catch the food successfully. Of course, they are not going to attack (攻击) someone every time they are playing around in a box. But it’s their natural behavior(行为) to act this way.

Another explanation is about how cats do with stress (压力). Cats are very poor at facing difficult situations. They find it easier to simply run away instead. A box offers them the chance to escape from the outside world. Staying in a small box gives them a sense of safety.

A scientist called Claudia Vinke did a study about the stress levels of cats. She first divided many cats into two groups. She gave the first group empty boxes and not the other. ________ After several experiments, she found that the cats in the first group were more friendly and comfortable with the people around them. As a result, it could be said that the cats got comfort and safety from being able to stay in the boxes.

It should be noticed that not all cats love boxes. But for most cats that do, these are some of the most widely believed reasons for why this is so.

“Meow!” Oh, it’s Molly. She is in her box, calling me to feed her.

10 . ① In our daily life, we often have such an experience: When we want to eat, being busy, we fight with the hunger. But when we’ve been hungry for a long time, we find us no longer hungry. Why does the sense of hunger go away even if we don’t eat?

② Why are people hungry? From a scientific point of view, the food we eat is changed into glucose (葡萄糖) for energy, and we feel hungry because we don’t have enough sugar. Our bodies can feel how much glucose there is in the blood. When there is not enough glucose, a person feels hungry. Hunger is not caused by having less food in the stomach, but the changes in glucose levels. So when you’re hungry, you don’t have to have meals.

③ When we have been hungry for a long time, why aren’t we hungry? In fact, the spare glucose can be stored. When we can’t eat for some reasons, our body will change this stored sugar into energy. When it arrives at a certain stage(阶段), our body will give us a message: the glucose is enough. So we don’t feel hungry anymore.

④ Is it OK not to eat when you’ve been hungry for a long time? No. It is harmful to the human body. When the stored energy is used up, the body breaks down fat to provide itself with energy. During this process, the person will feel dizzy, and may fall down easily. If worse, the protein (蛋白质)which is very important to the body also starts to break down, and we are in danger. If the worst, we may lose our lives.

⑤ For busy people, take some sweets with you on rainy days. If you have been hungry for too long, you mustn’t give up eating! Start with a piece of candy or some soup.

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