1 . Humans are not the only ones who underwent self-domestication. So did our close relatives, the bonobos, and the species we call our best friend. A tiny proportion of the genome differentiates dogs from wolves, and yet millions of dogs are comfortably curled up in our homes, while wolves move around at the edge of extinction.
When our research group began its work almost 20 years ago, we discovered that dogs also have extraordinary intelligence: they can read our gestures better than any other species. Wolves, in contrast, are mysterious and unpredictable. Their home is the wilderness, and that wilderness is shrinking.
But not so long ago the evolutionary race between dogs and wolves was so close, it was unclear who would win. Dogs, in fact, did not descend from wolves. Instead, dogs and wolves shared a wolflike ancestor.
Folklore supposes that humans brought wolf puppies into camp and domesticated them. Or as wolf expert David Mech wrote in 1974, “Evidently early humans tamed wolves and domesticated them, eventually selectively breeding them and finally developing the domestic dog from them.” But this story has not held up. Taming an animal occurs during its lifetime. Domestication happens over generations and involves changes to the genome.
So how did wolves turn into dogs? Back in the Ice Age, as our human populations grew more sedentary, we probably created more rubbish, which we then dumped outside our camps. These leavings would have included tempting pieces of food for hungry wolves. Not every wolf would have been able to scavenge, however. These animals would have had to be unafraid of humans, and if they displayed any aggression toward us, they would have been killed. After generations of selection for friendliness without intentional selection by humans, this special population of wolves would have begun to take on a different appearance. Coat color, ears, tails: all probably started to change.
Animals that could respond to our gestures and voices would be extremely useful as hunting partners and guards. They would have been valuable as well for their warmth and companionship, and slowly we would have allowed them to move from outside our camps to our firesides. We did not domesticate dogs. The friendliest wolves domesticated themselves.
1. What can be summarized about wolves and dogs from the first three paragraphs?| A．Wolves are smarter than dogs. |
| B．They are very much racially divided. |
| C．They are close relatives but dogs seem to be on the winning side. |
| D．Dogs have made their ways to indoor life while wolves to the wild. |
| A．diverse | B．limited |
| C．living in the same place | D．involving regular migration |
| A．Dogs evolved from wolves. |
| B．Selective breeding developed domestic dogs. |
| C．Taming and domesticating an animal are the same thing. |
| D．Friendliness as a quality translates into an evolutionary strategy. |
| A．From Wolf to Dog | B．Dog: Our Favorite Pet |
| C．An Intentional Domestication | D．A Competition Story between Wolf and Dog |
2 . Remember when your mom told you not to eat too many candy bars or sweets because they can cause tooth decay (蛀牙)? However, it turns out that chocolate can be more salutary to your teeth than you might expect. Recent studies show that chocolate can effectively fight against tooth decay, as if we need another excuse to eat chocolate.
Chocolate offers protection like fluoride, a main ingredient in most household toothpastes. Not only does chocolate protect our teeth, but it can do so very effectively. Studies show that chocolate has compounds that provide strong protection for teeth. One of the compounds in chocolate, CBH, is shown to protect even more effectively than fluoride.
Tooth decay happens when bacteria work to turn sugar into acids in our mouth. This is why eating foods with high sugar content can lead to more tooth decay. The compounds in chocolate, however, are anti-bacteria and can fight against bacteria in your mouth. The CBH compound in particular also works to strengthen tooth enamel (牙釉质), and protects against tooth decay.
Does this mean you can cat as much chocolate as you want without worrying about your teeth? It depends on the types of chocolate that you like. The protective effect of chocolate is most effective when you chew on cocoa beans. Of course, this option is not very appealing to; most people. A more tasty option is to choose dark chocolate with little sugar content, ideally no more than 6 to 8 grams per serving. For other types of chocolate with higher sugar content, the effect will be lessened. However, because of the protective compounds, it is still better for your teeth than other sweets and desserts containing the same amount of sugar.
1. The word “salutary” in paragraph 1 means?| A．Beneficial. | B．Harmful. | C．Familiar. | D．Useless. |
| A．It can help chocolate cure tooth decay. |
| B．It can effectively stop teeth from decaying. |
| C．It may protect teeth better than toothpastes do. |
| D．It may soon replace most household toothpastes. |
| A．By breaking down acids. | B．By building up compounds. |
| C．By fixing up tooth enamel. | D．By fighting against bacteria. |
| A．Chocolate plays the role of toothpaste. |
| B．Chocolate protects against tooth decay. |
| C．Chocolate is the best choice for teeth protection. |
| D．Chocolate is healthier to teeth than other sweets. |
3 . If you were to throw, say, a banana peel out of your car while driving along the motorway, that would be a completely harmless action, due to the fact that it’s part of a fruit — right? Actually, no. A banana peel can take up to two years to be naturally processed, and with a third of motorists admitting to littering while driving, that’s a whole lot of discarded banana peels. An orange peel and a cigarette butt has a similar biodegrading (生物降解) term to that of a banana peel, but tin cans last up to 100 years; and plastic bottles last forever, as do glass bottles.
Despite the fact that longer-lasting materials will serve to damage the environment and its animals for longer, we can’t merely measure the severity of a certain type of rubbish by its lifetime. For example, despite having a fairly short length of biodegrading time, more than 120 tons of cigarette-related litter is discarded in the UK every day.
It’s not a cheap habit either: to keep our streets clean annually costs UK taxpayers £500 million, and when you include our green spaces, that goes up to £1 billion. So, it’s not surprising that if caught fly-tipping you could face a £20,000 fine or even jail time and, if you disposed of something dangerous, the court could give you five years to serve. Regardless of how severe these punishments might seem, however, among the reported cases only 2,000 were found guilty out of 825,000, so we still have some way to go in making sure people obey the rules.
1. What does the underlined word “discarded” in para1 mean?| A．Harmless. | B．Processed. | C．Thrown. | D．Long-lasting. |
| A．Glass bottles. | B．Tin cans. | C．Cigarette butts. | D．Banana peels. |
| A．The severity of rubbish can be measured by its lifetime. |
| B．Quite a few people were found guilty of illegally littering. |
| C．Every year UK taxpayers spend £500 million keeping streets free of dirt. |
| D．Cigarette-related litter and peels can be ignored for their fairly short lifetime. |
| A．To inform readers of different biodegrading terms. |
| B．To call for people not to litter illegally. |
| C．To encourage people to use fewer plastic bags. |
| D．To stress the importance of good behavior. |
4 . Picture this: It’s 2003 and your family has just finished arguing over which Netflix movie video tapes to rent that week. Movies come in the mail and the family watch them throughout the week. Then, fast forward to 2008, and you have started to watch TV shows on Netflix’s new platform.
Now, let’s come to the present. You sit down and open up Netflix on your TV and scroll （滚屏） for a while. Then check HBO GO. Finally, check Disney+. Then realize that you’re paying for three different streaming services, maybe more.
Let’s return to Netflix. More generally, streaming. There are over 100 video streaming services available, as well as quite a few music streaming, including YouTube Music, Google Play, and etc. The streaming world, at least to some, is on its way to getting out of control, with each service requiring its own monthly entertainment subscription. We haven’t even taken into account subscriptions like Microsoft Office and email newsletters. Subscriptions started out as a service of convenience, but now, the oversaturation may have become burdensome. The services believe customers will pay more to get the content they want. However, statistics show a growing frustration among consumers. With so many options, they find it harder than ever to make a decision on what to pick.
Not only does the oversaturation of streaming result in confusing navigation, it also creates a financial burden for the consumers. Let’s say if you want to watch The Handmaid’s Tale and Game of Thrones, which belong to two different services, you would have to pay nearly $50 a month to access both services, meaning it’s potentially more expensive, than cable.
People cut their cords （细绳） and went the streaming route because it was simpler and cheaper. Now, it’s just as inconvenient and difficult as cable was, if not more so, and unless you’re limiting yourself to one service, it’s not cheaper. Streaming will survive because we’re in a Golden Age of Media and because each service is able to create high-quality originals. But Golden Ages don’t last, and bubbles tend to burst. Until the unavoidable day when some product or service proves streaming out of date, we must suffer the choices in front of us. The next time you are scrolling through Netflix, Hulu, or whatever, and the over-choice is killing you, maybe you should just go pick up a book instead.
1. What is mainly talked about in the first two paragraphs?| A．Social progress has promoted the quality of life in the past decade. |
| B．Technology innovation results in different ways of relaxation. |
| C．Changes in home entertainment have brought us more options. |
| D．Netflix has been developing its service patterns. |
| A．The large number of subscriptions. |
| B．The frustration caused by poor service. |
| C．The rapidly developing entertainment market. |
| D．The confusing navigation resulting from streaming. |
| A．improve user satisfaction | B．raise entertainment costs |
| C．diversify entertainment forms | D．realize the resource sharing |
| A．the streaming service will have a bright future |
| B．reading has an advantage over streaming service |
| C．there will be some better service to replace streaming |
| D．nothing can end streaming services as long as media exists |
5 . What happens when you cross stem cells from a frog heart and frog skin? Not much-that is, until you program those cells to move. In that case, you've created a xenobot, a new type of organism that's part robot, part living thing.
Now a team of scientists has used living cells from frog embryos and assembled them into entirely new life-forms. These millimeter-wide xenobots can move toward a specific target and pull themselves through after being cut.
These are novel living machines," says Joshua Bongarch a computer scientist and robotics expert at the University of Vermont who co-led the new research. "They're neither a traditional robot nor a known species of animal. It's a new living, programmable organism.
Xenobots borrow their name from Xenopus laevis, the name for the African clawed frog from which the researchers harvested the stem cells. They combined together well two different kinds of cells-heart and skin cells. The heart cells are competent in expanding and contracting, which aids the xenobot in locomotion, and the skin cells administer structure. Besides, they can't accomplish tasks without the help of computers.
By studying these curious organisms, researchers hope to learn more about the mysterious world of cellular communication. Plus, these kinds of robo-organisms could possibly be the key to drug transmission in the body or greener environmental clean-up techniques.
“Most technologies are made from steel, concrete, chemicals, and plastics, which degrade(降解)over time and can generate harmful ecological and health side effects the authors note in a research paper. "When these xenobots finally do stop working, they fall apart harmlessly.
“Promising as these organisms are, when we start to mess around with complex systems that we don't understand, we're going to get unintended consequences Michael Levin, a biophysicist and co-author of the study, says in a press statement.
1. What do we know about the xenobot?| A．It is not easy to degrade over time. |
| B．It can recover itself after being cut. |
| C．It will never die with a computer inside. |
| D．It is named after a kind of American frog. |
| A．Appearance. | B．Position. |
| C．Application. | D．Movement. |
| A．recycle waste in nature. |
| B．replace certain damaged organs. |
| C．deliver medicine inside patients. |
| D．improve communication technology. |
| A．Xenobots can be put into the market soon. |
| B．Xenobots are created totally by accident. |
| C．More research should be done on xenobots. |
| D．It is hard for people to understand xenobots. |
6 . These days, it's not unusual to see middle-aged men collecting Star Wars action figures, office workers wearing Hello Kitty accessories, or celebrities like David Beckham playing with Lego bricks. It's becoming more and more common to see adults taking an interest in toys, comic books and the activities that are traditionally associated with children. This phenomenon has given rise to a new word: kidult.
What lies behind the phenomenon? One is about adults' nostalgia （怀旧之情）for the carefree days of childhood, and this is especially true with today's fast-paced, stressful lifestyles. Another is about a societal change in recent decades where people are starting families later. As a result, they have more time and money to spend on themselves. Some adults could only window-shop for their dream toys when they were kids, but now they can afford that radio controlled car or high-priced doll they have always wanted.
Businesses have been quick to exploit the kidult trend, and the number of toy stores that target adults has risen. Companies are repackaging products from past decades and also bringing out new ones for adults. Lego, for example, has brought out an architectural series featuring landmarks from around the world.
Society traditionally disapproves of adults who refuse to put aside childhood interests, viewing the refusal as a sign of social immaturity and irresponsibility. Those who agree with this view sometimes claim that kidults are suffering from the pop-psychology concept known as Peter Pan Syndrome, an anomaly （异常）that people remain emotionally at the level of teenagers. On a grander scale, these kidult opponents （对手）argue that such delayed adulthood causes couples to marry later and have fewer children. This in turn can lead to shrinking national economies, for there needs to be a generational replenishment （补充）
of the workforce.
From the standpoint of kidults, though, this phenomenon is seen as nothing but harmless fun. Kidults insist that having youthful interests keeps them young, happy and creative, and their refusal to conform to society's acceptable tastes shows independent thinking. Besides, they argue that being part of the social trend of delayed adulthood is not purely a personal choice. The real causes include expensive housing, increased educational requirements for employment and poor work opportunities.
Whether the kidult phenomenon will continue to grow or prove to be a passing trend is anyone's guess. As the debate about it continues, remember that there is nothing wrong with being young at heart.
1. What does the kidult phenomenon refer to?| A．Adults act like children. |
| B．Adults have child-like tastes. |
| C．Adults go in for collecting toys. |
| D．Adults like playing with children. |
| A．Different living conditions. |
| B．More choices about toys. |
| C．High pressure of modern life. |
| D．Good memories of childhood. |
| A．Get used to. |
| B．Look forward to. |
| C．Take advantage of. |
| D．Make way for. |
| A．By strongly opposing kidult opponents. |
| B．By convincing readers to accept kidults. |
| C．By refusing to take a stand on the issue. |
| D．By presenting both sides of the argument. |
| A．Doubtful. | B．Positive. |
| C．Disapproving. | D．Uncaring. |
7 . Yangsigang Yangtze River Bridge, the double-deck suspension (悬浮) bridge with the longest span in the world, opened to traffic on Tuesday after five years’ construction, according to a statement from the constructor.
It is reported that the bridge is 4. 13 kilometers long, with 12 lanes in both directions on the main I bridge. It is a long-span suspension bridge with the largest volume in the world, China Railway Major Bridge Engineering Group said. The bridge connects the Hanyang and Wuchang and its opening will ameliorate the urban expressway system, relieve traffic pressure across the river, and drive development in the area, according to the company.
On both sides of the upper deck of the bridge, there is a two-meter-wide footpath, with eight rest and sightseeing areas, where people can enjoy the river scenery. The lower level is designed with two non-motorized lanes, each 2. 5 meters wide. A 1. 5-meter wide walkway is also a feature of each side of the floor so pedestrians (行人) can walk on the lower level without getting caught in the rain.
Chief designer of the bridge, Xu Gongyi, said, “Considering navigation and traffic volume, the main span of the bridge is 1, 700 meters, which is the second-largest in the world and also the largest in bridges of double-deck structure.”
According to Luo Ruihua, project manager of the bridge, the Yangsigang Yangtze River Bridge has set several records in the process of its construction. The designed tension of each of the two main cables (钢索) is 65, 000 tons.
From 2014 to 2019, builders have shown the world the speed of China. The bridge not only enhances Wuhan’s reputation as a “bridge museum”, but also represents a super project of a new era.
1. What does the underlined word “ameliorate” in paragraph 2 mean?| A．Keep. | B．Start. | C．Improve. | D．Show. |
| A．By giving examples. | B．By making comparisons. |
| C．By describing its principles. | D．By using data. |
| A．It will attract many foreigners to Wuhan. |
| B．It is friendly to pedestrians. |
| C．The cost of its construction is low. |
| D．It is the longest bridge of the world. |
| A．Negative. | B．Admiring. | C．Uncertain. | D．Grateful. |
8 . Now, it is winter and as you have probably noticed, virus are everywhere—runny noses, sore throats, nothing quite like the common cold to make you feel so uncomfortable. But experts believe that there is no link between cold weather and catching colds. So why are we particularly easy to catch colds this season?
Internal Medicine expert, Dr Meenakshi Jain of Max Hospital says, “One reason could be that people are likely to stay indoors, so the virus can spread easily. Also the virus grows strong and healthy under wet conditions.”
The common cold can be caused by any of up to 250 kinds of virus. The most common group of them is the kind of virus that hits the nose, which is called rhinovirus. Rhinoviruses cause a third and a half of all common colds.
“This kind of virus is spread through the nose and respiratory passages (呼吸道)，by touch, and by contact with particles (微粒) in the air that are created by sneezing or coughing,” says Dr Jain.
There is no way to treat the common cold. However, there are some tips that can help. Wash your hands regularly, so that germs get killed. Don’t touch your eyes, nose or mouth, which can limit your chances of infection (传染). Don’t share drinking glasses with anyone as this will prevent the spread of the virus. Drink lots of water. Make sure to eat enough fruits to boost your immune system (免疫系统). Get enough sleep and you’ll certainly become stronger.
1. What does the writer think will make you suffer most?| A．The common cold. | B．The winter. |
| C．Sore throats. | D．Runny noses. |
| A．the cold weather in the winter | B．the condition of the human body |
| C．the virus that hits people’s nose | D．the warm temperature in the room |
| A．damage | B．treat | C．change | D．improve |
| A．some ways for the virus to spread |
| B．the common cold can not be treated |
| C．exercise is important to people’s health |
| D．some tips on how to keep the cold away |
9 . A 15-year-old Indian girl, Kumari, who pedalled her injured father more than a thousand kilometres across India, has been invited to try out for the national cycling team.
In January, a motor-bike driver, Mohan Paswan, who made a living by carrying passengers in New Delhi, was injured in a traffic accident. After the accident, Paswan couldn't drive. So his daughter, Kumari took a train across the country to take care of him. But without income, Paswan could no longer afford the rent and they were running out of food. They decided to go home. With the last $20, the 15-year-old girl bought an old bicycle, and planned to take her father to their home village across India --- in a heroic, life-saving ride.
Kumari rode a bicycle with her father, sitting on the pillion(后座)and holding their belongings from Gurugram city, near New Delhi, to their village in the northeastern state of Bihar. They arrived home on May 16 after covering 1,200 kilometres (745 miles) in seven days.
The father and daughter's arduous journey on a second-hand bike bought with their remaining funds made headlines. It also caught the attention of the Cycling Federation of India, which offered Kumari the chance to try out for the country's team. "She covered this long and difficult distance in seven days with her father and some luggage too. I thought she has something in her endurance level. We can try her," chairman Onkar Singh told the journalist.
“She said she only wants to pursue her studies. We told her that we also take care of studies at our academies. Singh said the federation would test Kumari to see if she is suitable for competitive cycling.
There were also other people who praised Kumari's efforts, describing it as a "'beautiful model of endurance and love."
1. What made Kumari have to ride a bike back home?| A．That her father was injured. |
| B．That she could only afford a bike. |
| C．That her home village was far away. |
| D．That she wanted to join in the cycling race. |
| A．dangerous | B．lovely | C．pleasant | D．tough |
| A．Because she has extraordinary physical ability. |
| B．Because he didn't have anyone better than her. |
| C．Because she only wants to pursue her studies. |
| D．Because she is suitable for competitive cycling. |
| A．strong and caring | B．positive and confident |
| C．warm-hearted and brave | D．hard-working and beautiful |
10 . Throughout history scientists have risked their health and their lives in their search for the truth.
Sir Isaac Newton, the seventeenth century scientist, was very smart, but that didn't stop him from doing some pretty stupid things. In his laboratory in Cambridge he often did the strangest experiments. Once, while testing how light passes through lenses, he put a long needle into his eye, pushed it to the back, and then moved it around just to see what would happen. Luckily, nothing long-lasting did. On another occasion he stared at the sun for as long as he could bear, to discover what effect this would have on his sight. Again he escaped suffering permanent damage, though he had to spend some days in a darkened room before his eyes recovered.
In the 1750s the Swedish chemist Karl Scheele was the first person to find a way to produce phosphorus. He in fact discovered eight more chemical elements including chlorine , though he didn't get any praise for them. He was a very clever scientist, but his one failing was a curious habit of tasting a little of every substance he worked with. This risky practice finally caught up with him, and in 1786 he was found dead in his laboratory surrounded by a large number of dangerous chemicals, any of which might have been responsible for his death.
Eugene Shoemaker was a respected geologist. He spent a large part of his life studying craters on the moon, and how they were formed, and later did research into the comets of the planet Jupiter. In 1997 he and his wife were in the Australian desert where they went every year to search for places where comets might have hit the earth. While driving in the Tanami desert, normally one of the emptiest places in the world, another vehicle crashed into them and Shoemaker was killed on the spot. Some of his ashes were sent to the moon aboard the Lunar Prospector spacecraft and left there — he is the only person who has had this honor.
1. Which word is similar to the underlined word “permanent” in Paragraph 2?| A．Brief. | B．Lasting. | C．Slight. | D．Ordinary. |
| A．He was killed by tasting phosphorus. |
| B．He killed himself with some dangerous chemicals. |
| C．His habit of tasting chemicals might account for his death. |
| D．He got a large number of honors for discovering many chemical elements. |
| A．He was knocked over and died in a desert. | B．All of his ashes were placed on the moon. |
| C．One comet of Jupiter was named after him. | D．A spacecraft carrying him traveled around Jupiter. |
| A．Three great scientists' famous experiments. | B．Three great scientists' great achievements. |
| C．Three great scientists' sacrifice for the truth. | D．Three great scientists' special honors. |
