Loudness in the air
BOOM! That’s a word we often use to describe a loud sound. It’s also part of the term “sonic boom (音爆)”, which is something that happens when air is pushed so strongly and quickly that it creates a loud noise.
On March 20, rare daytime meteor (流星) created sonic boom over parts of the UK and France, according to Live Science. The meteor flew through the sky so fast that it could hardly be seen—but it could definitely be heard.
So how exactly are sonic booms made? You can think of air as being like water. When something moves through water, you can see ripples (波纹). If the object moves very quickly, the ripples start to run into each other.
The same thing happens in the air, even if it can’t be seen. When the object moves faster than the speed of sound, the air is pushed hard, and it compresses (压缩) like the ripples on water. This will create a sound wave that is very loud, which is a sonic boom.
Actually, lots of things can make sonic booms. When you go to the park and see people play with whips and tops (鞭子和陀螺), you might hear a tiny sonic boom when they crack (重击) the whip. Aircraft (飞机) that travel faster than the speed of sound can also make sonic booms.
A strong sonic boom can cause damage to windows or buildings, although the possibility of this is very low, according to the US Air Force. The loud sound can also influence people on the ground and even cause hearing loss. That’s why supersonic aircraft are only allowed in times of war.
1. When can a sonic boom happen?2. What created a sonic boom over parts of the UK and France on March 20?
3. Can you usually see a sonic boom in the air?
4. How can an aircraft create sonic booms?
5. What can a sonic boom cause?
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It is one of the most famous books in the world: yet it has no story and no interesting characters, no exciting beginning and no satisfying ending. And yet this book keeps being printed and it keeps growing. At its last printing, it was 20 volumes (卷), with nearly 22,000 pages. This book is one of the most famous dictionaries in the English-speaking world, the Oxford English Dictionary.
The Oxford English Dictionary or OED for short, began in 1857 as just an idea of a group of people who thought the world needed an English-language dictionary to show the history of English words from 1150 CE to the present. It wasn’t until the late 1870s, however, when James Murray joined the project that it began to grow. Murray planned for a dictionary of about 6, 400 pages in four volumes, completed in 10 years.
James Murray (1837-1915) did most of his work in a small metal building called the Scriptorium. That small building, hot in summer and cold in winter, was the place where Murray and his assistants (助手) collected millions of pieces of paper, each one with a word and an example sentence or phrase written on it. Murray and his assistants worked hard, but after five years they had only reached the word ant!
It was not until 1928 that the dictionary was told to the public completed and published: 10 volumes with over 400,000 words and phrases. James Murray did not live to see the completion of his life’s work, he passed away in 1915, over ten years before OED came out.
As soon as the dictionary was published, however, the editors started to update (更新) it! In 1933, the Oxford English dictionary was reprinted in 12 volumes. Between 1972 and 1986, four more volumes were added with new technical and scientific vocabulary and words from other English-speaking countries, such as Canada, the USA, Australia, New Zealand, and South Africa. In 1989, the entire (整个的) dictionary was reprinted in 20 volumes! Three years later, all 20 volumes were put onto CD, and the entire dictionary is available online today.
With about 600,000 words and three million quotations (引语) from over 1,000 years of English, the OED not only records where the English language has come from but has also become an important part of the history of English-speaking cultures around the world.
The book that keeps on growing | ||
Facts and features | ![]() ●It was 20 volumes with nearly 22,000 pages. ●It has about 600,00 words and 3 million quotations from over 1,000 years of English. ●Although it has no story or interesting characters, etc., it keeps being printed and it keeps growing! That is to say, it is | |
The Oxford English Dictionary | ||
![]() | began just as an idea to show the history of English words from 1150 CE to the present. | |
began to grow when Murray joined. Murray with his assistants worked hard, patiently and carefully under | ||
was completed and published in 10 volumes. | ||
was reprinted in 12 volumes. | ||
was added up to | ||
was reprinted in 20 volumes. | ||
was put onto CD. | ||
is available online. | ||
Importance and values | ●It is one of the most famous dictionaries in the English-speaking world and also one of the most famous books in the world. ●It is not only |
【推荐2】Touch down to Earth
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China welcomed three heroic astronauts Zhai Zhigang, Wang Yaping and Ye Guangfu home on April 16. This return ended the Shenzhou XIII astronauts’ six-month space mission. It also marks a major (重大的) breakthrough for China’s efforts in space.
In order to return home safety, they did a lot of preparation before leaving the space station.
If you are coming home after a long journey, you have to pack up. For astronauts in space, besides their personal belongings, they “packed” experimental data (数据) and samples, so they would be further researched on Earth.
The astronauts had to tidy up a large number of materials, including goods on the Tianzhou 3 cargo (货物) spacecraft, according to Zhong Weiwei, a researcher at the China Astronaut Research and Training Center.
Since the space station had no room service, the three astronauts needed to “clear the house” themselves. They collected a great amount of waste. This included leftover foods, sanitary (卫生) waste and waste from in-orbit experiments. The waste was then put into the orbital module (轨道舱), which burnt up as it reentered Earth’s atmosphere.
They also had to put all equipment in place correctly since there would be a gap of more than one month before the astronauts of Shenzhou XIV enter the space station, according to Zhong. They needed to make sure some items, such as gym equipment, were fixed to the walls to avoid floating and slipping (滑落).
Astronauts experienced microgravity for long periods of time during their stays on the space station, which had an effect on their bodies. This included a loss of fluid (体液) muscle atrophy (萎缩) as well as bone loss.
To ensure their safe and sound return, the three astronauts had been doing physical exercises to train their muscles for the return to Earth. Based on their in-orbit physical examinations and data, experts had customized (定制) exercise plans for each of them to ensure a safe landing.
Just like a house that will be vacant (空着的) for a long time must have it’s water and power switched off, astronauts checked everything before they left. Based on experience at home and abroad, they checked and adjusted 40 to 50 items to ensure that the space station could transmit valid parameters (参数) to the ground during subsequent unmanned missions.
1. When did the three astronauts return to earth safety?2. What did they “pack” experimental data and samples for?
3. Where did they put the waste they collected?
4. How did experts help the three astronauts return?
5. What do you think of staying in space? Why do you think so?
Barbara Wells exercised every morning. She woke up at 6:00 a.m. She ran about two miles before she went to work. But Barbara’s legs and back started to hurt. She did some exercise before she ran. But her legs and back still hurt. She ran slower, but the pain didn’t stop. Barbara talked to her doctor. The doctor said, “Don’t run in the morning. Try to exercise later in the day. That is the time when your body is at the right temperature for exercise.” Her legs and back didn’t hurt anymore.
Today, doctors are learning more about chronobiology, the study of the biological clock. They are learning about the importance of time to our bodies. For example, it is best for people to go to sleep on time every night and to eat only when they’re hungry. Also, doctors discovered that some illness, such as heart problems, happen most often in the morning. This information tells them that the best time to take heart medication is at night. When patients take heart medication at night, they may prevent a heart problem in the morning.
Many doctors believe chronobiology can help us live healthier lives. It may be the right time to listen to these doctors!
1. Do we all have the biological clock inside our bodies?
2. How far did Barbara Wells run every morning?
3. What’s the best time to take heart medication?
4. According to the passage, what should you do to live a healthier life?
The Rocky Mountains are a large group of mountains on the North American continent(洲). The Rockies are found in the western part of North America. They stretch(连绵) from Canada in the north to the United States in the south. The southern part of the Rockies ends in the state of New Mexico.
The Rockies are the longest mountain range in North America. They have many high peaks(山峰). The highest is Mount Elbert in Colorado. It is three miles high.
In the summer, the Rockies are warm and dry, though it does rain sometimes. During the winter, the weather is wet and cold. Heavy winter snow falls in the higher parts of the Rockies.
Many people like to visit these mountains. They ride bikes, hike on trails, ski, or fish. A special area called Rocky Mountain National Park is in Colorado. The national park is reserved(留出) for people to visit. Visitors to Rocky Mountain National Park can see the wild animals that live there. These animals include elk(麋鹿), moose(驼鹿), mountain goats, and mountain sheep.
In the summer, the Rockies are warm and dry, though it does rain sometimes. During the winter, the weather is wet and cold. Heavy winter snow falls in the higher parts of the Rockies.
Many people like to visit these mountains. They ride bikes, hike on trails, ski, or fish. A special area called Rocky Mountain National Park is in Colorado. The national park is reserved(留出) for people to visit. Visitors to Rocky Mountain National Park can see the wild animals that live there. These animals include elk(麋鹿), moose(驼鹿), mountain goats, and mountain sheep.
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Wood’s cycad is a striking plant, tall with a green crown and bright orange cones. Found in a Zululand forest in 1895, it is the only cycad of its kind, and a male. “The loneliest plant in the world, right here,” a guide tells visitors touring the Durban Botanic Gardens in South Africa. Without a female it will never reproduce, though measures have been taken to make clones of it.
Cycads date from the time of the dinosaurs. But some of the kinds might not be around much longer. They are the world’s most threatened plant group. South Africa’s cycads, most of which are found nowhere else in the world, are especially endangered. All cycads are dioecious(雌雄异株的), so that seed production is no longer possible with the rarest of the species. And surprisingly, it is those who love the cycad most that pose the biggest danger—collectors who want exotic varieties for their private gardens. Slow-growing adult cycads, some hundreds of years old, sell for tens of thousands of dollars. “People see them as a status symbol,” says the senior gardener Phakamani Xaba. In fact, 25 of South Africa’s 38 cycad species are threatened with extinction. Two of the world’s cycad species have been wiped out in the wild since 2003. With wild stocks diminishing, thieves have turned to breaking into protected gardens and reserves.
To prevent theft, plants have been fitted with microchips, but thieves use X-ray scanners to find them and hack them out. Rare cycads are now sprayed with special invisible paint. Scientists are testing radio frequency identification tags on cycads that could send out alerts.
The major difficulty in stopping the illegal trade is the fact that leaves removed for transport, it is difficult to distinguish the trunk of an endangered species from one that is legal to sell. A DNA database, using gene sequences, is being tested to help with identification.
Xaba says it is probably too late to save some cycad species. He feels sad that collectors are almost never caught. For extreme collectors, rarity only makes a cycad more desirable.
Fortunately, some governments have been aware of the problem. Take South Africa as an example, strict regulations on the illegal trade of rare cycads are being implemented.
根据短文,在下面表格中填入恰当的内容完成摘记,每空不超过三个单词。
Cycads: The | |
A typical | Wood’s cycad has only one |
Present situation | •The number of the wild cycads is •Two cycad species have died out and twenty-five are at risk of extinction. |
of the situation | •Cycads are dioecious, which makes it hard for the rare ones to fertilize. •Cycads face the serious problem of |
Difficulty in conservation | |
of conservation | •Scientists use technologies to save cycads such as putting •Governments make special |
【推荐3】Whenever you walk past a cafe, you might be drawn in by the smell of freshly made coffee. But the minute you try this dark drink you will regret it, because it tastes like bitter Chinese medicine.
Why does something that smells so good taste so bad? Many people are curious about this, but now scientists say they have found the answer—it lies in our “second sense (感觉) of smell,” according to the Telegraph.
“We have two senses of smell,” explained Barry Smith, professor of the University of London. “One is when you breathe in things from the environment, and the other is when the air comes up the nose and is breathed out through the nose.”
When we drink coffee, for example, the act of swallowing (吞咽) sends a burst of smell up the back of our nose from inside the mouth. This wakes up the second sense of smell in our brain. But it is weaker and less sensitive (敏感的) to flavors (味道). As a result, it gives us a completely different feeling.
In fact, the second sense of smell plays a big part in our eating experience. It may be common sense that we smell through our nose and taste using our tongue (舌头). But the truth is 80 percent of what we think of as taste actually reaches us through smell. Just hold your nose while eating and you will notice that your tongue can only catch a very small part of the flavor.
1. What does the 1st paragraph show us?2. Why does something that smells so good taste so bad?
3. What is the “second sense of smell”?
4. Which body parts play a role in sensing the flavor?
5. According to the last paragraph, how do we get the real taste when eating, by smelling or tasting?
6. What does this passage mainly talk about?