In the 1800s, there was a metal that was even more valuable than gold. It is aluminum. Rich ladies wore jewelry made of aluminum. Kings served their guests on aluminum plates.
However, aluminum is not rare. In fact, it’s the most common metal.
Only it was difficult to get it. For a long time, no one knew how to get it out of bauxite. As far back as the 1700s, scientists thought bauxite held metal. But they didn’t know what kind. They tried heating the rock to different temperatures. They also put into acids and salts. But no luck. Finally, in 1825 they managed to get a little aluminum. It took another 20 years to get the metal, although in a very small amount.
In 1884, an American named Charles Hall was in chemistry class when his teacher handed around a piece of aluminum. He told the students that they could change the world and get rich if they could invent a cheaper way to make it. Charles Hall did it.
The main challenge was how to separate the aluminum from oxygen. Aluminum really, really likes oxygen. Aluminum and oxygen will stick together even at very high heat. Hall’s way was to add electricity to knock oxygen and aluminum apart.
Meanwhile, in France, chemist Paul Heroult had exactly the same idea! They shared credit for the discovery. The Hall-Heroult Process is still used today. And Hall’s aluminum company became the largest in the world.
Soon there was cheap aluminum for all. Engineers loved it. Aluminum is light and strong. Mixing aluminum with other metals can make them lighter and stronger.
Today, aluminum is all around us, in cars, airplanes, buildings, bikes, computers, cooking pots, soda cans, and much more.
What’s more, ________. Getting new aluminum from old aluminum products uses 90% less energy. It’s much cheaper and creates less pollution. In fact, thanks to recycling, 75% of all aluminum ever produced is still in use! So the next time you see an old soda can, don’t think of it as trash. Think of it as one of Earth’s most valuable metals, even if it doesn’t cost as much as gold now.
1. According to the passage, aluminum ________ in the past.| A．was not liked by wealthy people | B．was not a common metal on the earth |
| C．was not easy to get out of bauxite | D．was not as valuable as gold in the 1800s |
| A．salts | B．ice | C．heat | D．electricity |
| A．aluminum is easy to make |
| B．aluminum is easy to recycle |
| C．aluminum products can be used for a long time |
| D．aluminum products don’t cost much money now |
| A．The Common Rock — Bauxite | B．The Great Chemist — Charles Hall |
| C．The Magical Metal — Aluminum | D．The Helpful Idea — Hall-Heroult Process |
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【推荐1】When we have small cuts in the skin, something strange may happen. The cuts are able to heal themselves in a couple of days. How does this happen? Read on, and you will find out the secret.
Every living thing on the earth is made up of cells. Cells grow and make new cells. Most cells are very small and we can't see them with our eyes. Different cells have different uses. Our skin cells are special ones. The cells on the outside of our skin are old dead cells. New skin cells are right under the outside. These are the living skin cells. They work for our bodies. They help protect our bodies and heal cuts.
Our bodies make skin cells all the time. As the old cells fall off, new cells grow in the same place. Each person makes about 18 kg of skin cells during his or her life. Outside skin cells fit together closely with no gaps between them. When you cut yourself, you can harm your skin cells. A small cut will not be harmful. Your skin will quickly heal itself by making new skin cells. How do skin cells work? First, the cells near the cut get bigger and move into the gap. Next, these bigger cells meet in the middle. They form a new layer (层) of skin cells. Finally, new cells will grow until the gap disappears. In this way, your skin can grow and get well itself. How amazing the small cells are! Next time you have a cut, don't worry about it. Maybe in a few days, you will be surprised to find it healed.
1. The underlined word “gaps” in the passage means “ ______ ” in Chinese.| A．突起 | B．条纹 | C．缝隙 | D．代沟 |
| A．are large and we can see them with our eyes |
| B．can heal few cuts themselves |
| C．are in everything on the earth |
| D．can grow and make new cells |
| A．a→b→c | B．b→c→a | C．a→c→d | D．b→a→c |
| A．Each person can make 18 kg of skin cells every day. |
| B．Different cells have different uses in our bodies. |
| C．The skin cells have little work to do in the body. |
| D．Every living thing on the earth is made up of skin cells. |
| A．How Skin Cells Heal Cuts |
| B．The Importance of Skin |
| C．How to Protect Our Fingers |
| D．The Importance of Cells |
Do you play with your phone before bedtime? You may want to read a book instead. According to a US study, looking at screens at night can cause us to sleep poorly.
In the evening, our bodies make melatonin (褪黑素). Melatonin helps us feel sleepy and relaxed. It is an important part of our sleep cycle (周期). Our electronic screens stop that cycle from working normally.
Why? Phones, computers and TVs make blue light. Blue light stops our bodies from making melatonin. Even just a little bit of blue light can have an effect. Eight minutes of blue light can keep your brain “awake” for another hour, according to the study. Even if you fall asleep, you may have lots of dreams. Your brain won’t have a good rest.
It’s even worse if you play an exciting game before bed. Games make our hearts beat faster, so we have a harder time falling asleep. Then, when we fall asleep, we don’t get enough “deep sleep”, which results in poor health.
Use these tips to get a good night’s sleep:
Have a relaxing routine every night. Take a warm shower or read a book.
Sleep in a dark, quiet room that is not too warm or too cold.
Count sheep. It’s the oldest trick, and it can actually work!
Don’t eat a big meal or have caffeine（咖啡因）. Instead, drink milk.
Don’t run around or exercise three hours before bedtime.
1. What can we learn about melatonin?| A．It helps us fall asleep at night. | B．It makes us feel hungry and tired. |
| C．Too much of it makes us sleep poorly. | D．It stops our sleep cycle from going normally. |
| A．They cannot make us feel relaxed. | B．The blue light breaks our sleep cycle. |
| C．Our brains need more time to make dreams. | D．They make more melatonin than our bodies need. |
| A．Getting enough deep sleep is important. |
| B．Playing games helps us go to sleep quickly. |
| C．Our hearts beat more slowly when we play games. |
| D．It’s good for us to play exciting games before bedtime. |
| A．How scientists carry out the study. | B．Why some people have lots of dreams. |
| C．Why people should have enough deep sleep. | D．How playing with phones leads to poor sleep. |
【推荐3】Human, Don’t Come too Close
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When we see babies or pets, we can’t help gently touching them to show our love. And they give us happy feelings back. But a recent study shows that it’s different for plants.
A study, published in The Plant Journal, shows that plants don’t “like” to be touched. That’s because touching changes their genes (基因) and, even worse, can slow their growth.
Professor Jim Whelan of the La Trobe Institute in Australia gave an explanation. “The lightest touch from a human, animal, insect, or even plants touching each other in the wind, leads to a huge gene change in the plant,” Science Daily reported.
In order to test the theory, the scientists did an experiment on plants. They grew a number of plants to the age of four weeks. Then they touched them with a paintbrush every 12 hours over a 36-hour period.
They found that as a response to the touch, the mitochondria (线粒体) in the plants had been partly destroyed. The mitochondria, as Science Alert noted, are the “powerhouse of the cell (细胞)”. The mitochondria produce energy for the rest of the cell in both animals and plants.
If this “powerhouse” is weakened, the plants will lose a large amount of energy that should have supported their growth. Whelan further explained to Science Daily, “If the touching is repeated, then plant growth is reduced by up to 30 percent.”
Although the process does have a strong effect on plants, usually the plants survive. Touching changes the plants, but it’s not necessarily a bad change.
According to Science Alert, frequent touching or moving plants will make them grow shorter than other ones. The researchers believe this change, in some way, could be helpful. It may help plants fight threats to their health such as insects and bad weather.
The new research findings have led to a deeper understanding of the plants’ response to touching. And the research might “open up new ways to reduce sensitivity (敏感性) and improve growth in the future”, Science Alert reported.
1. Why did the scientists do the experiment?| A．To test if touching can change the genes of plants. |
| B．To show that plants’ and animals’ genes are different. |
| C．To tell when touching has effect on plants and animals. |
| D．To find out why some plants grow more slowly than others. |
| A．Repeated touching shortened the plants’ life by four weeks. |
| B．Touching slowed down plant growth by reducing energy for growth. |
| C．Repeated touching made plants die sooner than they were expected to. |
| D．Mitochondria in the plants couldn’t produce energy because of touching. |
| A．The plants will be more likely to be attracted by insects. |
| B．The plants will be more easily harmed by bad weather. |
| C．The plants will be less sensitive to being touched. |
| D．The plants will be better at fighting dangers. |
【推荐1】Death is a part of life and it’s natural to grieve when an animal you love dies. Grieving—the feeling reaction to death—is an important part of the healing process (康复过程).
Deal with the loss of a pet
A pet is part of the family, so when they die, it can be very difficult and upset for everyone who loved them. It’s a big change to get used to and it’s natural to miss them. It can help to remember that your pet can no longer feel hungry, cold or pain.
It’s OK to feel sad, angry, shocked or to feel hard to believe they’re no longer alive. There’s no right way to feel or to grieve. As people are all different, the length of time it takes for you to feel less sad may not be the same as for someone else. Dipti Solanki, who helps people with their grief, says, “In my opinion, your feelings matter and are normal after you lose a pet. They can feel really big and difficult to control.” It’s OK if sometimes you smile or laugh and don’t feel so sad. It doesn’t mean you loved your pet any less.
Share to overcome your bad feelings
It’s better to talk than to keep your thoughts and feelings to yourself. Solanki says, “It’s really important that you talk about feeling sad or afraid to your friends, because once you do, you will start to feel calmer and less alone. After you share your feelings, they become less serious and easier to deal with.” Talking about your pet helps to keep it memories alive because you remember the time you spent together.
Celebrate your beloved pet
It can help to remember the funny things your pet did, what you loved about them and the happy time you shared. As well as talking about them, you can get creative. Print out photos of your pet and make them into a collage (拼贴画). You can also draw or paint a picture of them. Or write a story about something you did together or how they made you feel.
1. What does the underlined word “grieve” in Paragraph 1 mean?| A．To feel sorry for losing someone you love. |
| B．To become lonely for living away from pets. |
| C．To become tired for taking good care of pets. |
| D．To feel happy for leaving something unpleasant. |
| A．To tell an interesting story. |
| B．To support the writer’s opinion. |
| C．To give readers more facts. |
| D．To compare different examples. |
| A．The length of the healing process is the same. |
| B．Sharing bad feelings is like cutting them in half. |
| C．Keeping the feelings to yourself is a proper way. |
| D．It’s not necessary to feel sad for the death of pets. |
| A．Talk to its photos or collages as if it were still alive. |
| B．Never talk about it as if it never appeared in our life. |
| C．Buy a new pet as soon as possible to forget the dead one. |
| D．Remember it needn’t experience coldness or hunger anymore. |
If you visit the classroom of Japan, you can play the games Japanese children play. You also have some special Japanese foods. In the classroom of Mexico (墨西哥), there are tomalleys (龙虾肝) and chips to eat.
In the afternoon, all the students, teachers and parents watch the dances. There are lots of dances. These dances are beautiful. People enjoy the shows.
I enjoy International Day very much.
1. ‘International Day’ is a special festival in ___________.
| A．Japan | B．Mexico | C．America | D．our school |
| A．In the morning. | B．In the afternoon. |
| C．In the evening. | D．All day. |
| A．Tomalleys and chips. | B．Turkey. |
| C．Pizza. | D．Pumpkin pie. |
【推荐3】In recent years, a number of ancient Chinese inventions have been well known around the world. Here are four of them.
Chinese Zhusuan Zhusuan was first discovered by Liu Hong. With a long history of 1,800 years, it is a symbol of the wisdom of the ancient Chinese people. It uses an abacus, which is considered as the world’s oldest computer. It is different from the modern computer. As the world develops so fast, it has lost its role in the 21st century. | The Shadow Play The shadow play is one of the oldest plays in China. It first appeared in ancient Chang’an over 2,000 years ago. It became popular in the Tang and Song dynasties. At that time, it brought people pleasure as modern movies and TV plays do. When the shadow play is put on, the actors sing along with the music and control shadow tools at the same time. |
The 24 Solar Terms It is called the fifth great invention of China. The 24 Solar Terms is a system that shows the relationship between the climate and agriculture. And it plays an important role in Chinese agricultural production and people’s daily life. | Paper Cutting With a long history of over 1,500 years, paper cutting has been very popular among the Chinese people. The first paper-cut appeared in the Northern and Southern dynasties. Paper cutting had a close relationship with Chinese rural festivals. People put paper-cuts on walls, windows and doors. |
1. Which invention has a history of 1,800 years?
| A．Chinese Zhusuan. | B．The Shadow Play. |
| C．The 24 Solar Terms. | D．Paper Cutting. |
| A．An old famer created the 24 Solar Terms. |
| B．It is important for farmers to plant crops. |
| C．It is called the sixth great invention of China. |
| D．It shows the relationship between the weather and the people. |
| A．Liu Xiang was the first person to invent Zhusuan. |
| B．Th shadow play was put on walls, windows and doors. |
| C．The 24 Solar Terms was used to predict the weather. |
| D．Paper cutting had a close relationship with Chinese rural festivals. |
| A．In the Song and Qing dynasties. |
| B．In the Tang and Ming dynasties. |
| C．In the Tang and Song dynasties. |
| D．In Northern and Southern dynasties. |
| A．Culture. | B．Music. | C．Science. | D．Sports. |
