期末复习阅读理解2024-2025学年沪教牛津版八年级英语下册

8B 期末复习阅读理解 Unit 5 Endangered Animals A ①Swifts (雨燕) live mostly in the air. These small birds are among the fastest animals on Earth. In fact, swifts can go two or three days without touching the ground! To get used to life in the sky, swifts use their speed and the saliva in their mouths. ②Swifts can fly faster than 100 miles per hour. That’s because their wings are like boomerangs (回力镖). This shape of the wings helps them to fly much faster. They can also move one wing faster than the other, which allows them to make sharp turns without slowing down. Making fast, sharp turns helps swifts catching flying bugs to eat. ③The saliva (唾液) helps swifts catch bugs to feed their young. It is sticky, like glue. Swifts often fly into clouds of bugs such as mosquitoes and open their wide mouths to catch as many insects as they can. The bird collects insects in its mouth gradually and holds the insects in a sticky ball of saliva. One food ball can contain nearly 1,000 bugs. ④Swifts also use their saliva as glue to build their nests. The birds catch feathers in the air and stick the feathers together to build a strong nest on the side of a cliff (悬崖) or building. Swifts’ short feet are not good for walking or standing on land for long. But their sharp claws (爪子) allow them to stick to rocks and walls so they can take a brief rest before returning their lives in the sky. 1．Which of the following best show the structure of the passage? A． B． C． D． 2．The second paragraph mainly talks about ________. A．how fast swifts can fly B．how swifts turn around in the sky C．why swifts make sharp turns D．why swifts can fly and turn so fast 3．Which of the following is TRUE about swifts? A．Swifts don’t usually live on land because of their wings. B．Swifts can fly for a long time because of their small bodies. C．Swifts can’t walk for a long time because of their short feet. D．Swifts can catch nearly 1,000 bugs in one go with the saliva. 4. Why are swifts able to make sharp turns without slowing down? A. Because their boomerang-shaped wings help them fly faster. B. Because they can move one wing faster than the other. C. Because their bodies are so small that they experience little air resistance (空气阻力). D. Because they usually fly low and slow and experience less air resistance. 5．Which of the following is the best title for the passage? A．Life in the Sky B．A Small Pet C．The Fastest Speed D．The Special Saliva B Can dolphins talk? Maybe they can’t talk with words, but they talk with sounds. They give information and show their feelings with sounds. We call a group of fish “a school”. They don’t study together, but they travel together in a group. Dolphins are mammals (哺乳动物), not fish, but they swim together like fish in a school. Dolphins talk to the other dolphins in the school. They tell each other when they are happy or sad or afraid. They say “welcome” when a dolphin comes back. They talk when they play. They make a few sounds above water. They make many more sounds under water. People cannot hear these sounds because they are very high. Scientists make tapes of the sounds and study them. Dolphins can’t breathe underwater, so every time a dolphin needs to breathe, it has to come to the water surface to breathe and supply (供应) its lungs (肺) with oxygen. Yet a dolphin might only be able to hold its breath for about 15 to 17 minutes. Dolphins are smart animals. Sometimes people catch dolphins for large sea parks. People can watch wonderful dolphin shows in a sea park. But dolphins don’t like to be away from their school. They miss their group members. They are sad and lonely when they are in the sea park. Dolphins are friendly to humans. There are many stories about dolphins. They help people in trouble and sometimes they save a person in danger. People love dolphins and don’t want to hurt or kill them. They say that dolphins bring good luck. Many people believe this. 1．The underlined expression “a school” (in Para.2) refers to ________. A．a group of fish swimming together B．a dolphin show in a sea park C．a special kind of animals in the sea D．a place for kids to study together 2．Which of the following about dolphins is TRUE according to the passage? A．They like to study together. B．They can show different feelings to each other. C．They can breathe underwater. D．They are happy to stay in a sea park. 3. What can follow the last paragraph if we were to continue the passage? A. The biological mechanism (机制) that allows dolphins to make high-pitched sounds B. The ways in which people catch dolphins and keep them in the sea park C. True stories of dolphins helping and saving people in danger D. The dicoveries scientists made on dolphins living in the ocean 4. Where can you most probably find this article? A. In a fashion magazine B. In a newspaper C. In a travel guide D. In a science magazine 5．The best title for the passage is ________. A．Fun Facts about Dolphins B．Special Schools for Dolphins C．Nice Stories about Dolphins D．Beautiful Sounds by Dolphins C With two in five plant species（物种）at risk of disappearance, the Germplasm Bank of Wild Species（中国西南野生生物种质资源库）, or GBOWS, in Yunnan Province is racing against time to protect the nation’s plant species. Founded in 2007, GBOWS is a research and preservation（保存）bank for rare and endangered plants and animals. As the largest bank of wild species in Asia in terms of species, GBOWS has preserved 85,046 seeds from 10,601 species and 60,262 biological samples（生物样本）of 2,203 animal species. The number of seeds at GBOWS is close to that of the world’s biggest seed bank — the Millennium Seed Bank in the United Kingdom. So how does the bank work? Scientists collect the endangered and useful wild species and send them to the seed bank. Once the seeds arrive at GBOWS, they’re dried and preserved in a special room. X-rays will make sure the seeds are undamaged and no insects are hidden inside after they are cleaned and separated from broken ones. The seeds are then frozen（冷藏）, preserved in glass bottles and placed in a huge room at -20℃ for long-term preservation. Each bottle has a barcode（条形码）By scanning it, scientists can view detailed information about the seeds inside. The bank works with many international organizations on collection, exchange and research. It has 2,176 sets of seeds from 45 countries and regions, with each set including thousands of seeds. “As China has rich and special plant and animal species, we plan to increase the number of our collections and conduct further research to protect endangered species,” says Li Pei, a worker at GBOWS. “If the world ends one day, these collections will bring hope of a new beginning to life on Earth.” 1. What’s the purpose of Paragraph 1? A. To show us how to name a bank. B. To introduce the topic of the passage. C. To call on people to value their time. D. To tell us the importance of plant species. 2. Which of the following is correct? A. GBOWS has 10,601 animal species in total. B. All of the seeds at GBOWS are found in China. C. The number of seeds at GBOWS is the largest in the world. D. Other Asian banks have fewer wild species than GBOWS. 3. Which is the right order according to Paragraph 3? ① The seeds are sent for X-rays. ② The dried seeds are put into a special room. ③ The seeds are put into a room at -20℃. ④ The broken seeds are taken out. A. ②→④→①→③ B. ②→①→④→③ C. ④→②→①→③ D. ④→①→③→② 4. According to Li Pei, the work at GBOWS is ______. A. creative B. challenging C. meaningful D. dangerous 5. What’s the passage mainly about? A. The bank’s ways to preserve seeds. B. The contributions GBOWS has made. C. China’s efforts to protect plant species. D. A bank that collects seeds for the future. Unit 6 Pets A In September, something terrible happened on the west coast of Tasmania, Australia. As many as 380 pilot whales became stranded（搁浅）in shallow water there and later died. This might have been Australia’s largest stranding event on record, the BBC reported. But this large amount of whale stranding is not uncommon. For centuries, it has happened all over the world and has puzzled scientists. Scientists say the cause is often unknown. But they have offered many different explanations. Some say the whales chase small fish for food and end up in shallow water because they are not paying attention to where they are going. Others think the stranding has something to do with Earth’s geomagnetic field （地磁场）. They say that a geomagnetic compass in whales’ brains controls their position. Unusual changes in Earth’s magnetic field can affect the whales’ compasses and send them in the wrong direction. Another explanation suggests that stranding is caused by the close relationships that whales have. Pilot whales travel in large groups. One lead whale might mistakenly lead the whole group to shallow water. “And if one gets into trouble, the others will not leave,” said Sheryl Gibney, a leading biologist from New Zealand. “Some will come in and try to help. They get trapped on the beach and then more will come.” The whales are trapped by mistake or out of sympathy（同情）. Once they get stranded, they will likely die. According to the National Oceanic and Atmospheric Administration of the US, less than 10 percent of all stranded whales survive. 1．What do we know about the stranding in Australia? A．It happened on the east coast of Australia. B．It caused the death of over 300 pilot whales. C．It is commonly seen in September each year. D．It was the largest stranding event in the world. 2．According to Gibney, the pilot whales are the animals that ________. A．are kind to each other B．are easy to lose direction C．are too huge to float in the sea D．are smart not to follow the leading whale 3. What does the underlined word “compass” in paragraph 4 mean? A. Whale’s vocal cord that can send out sounds B. Whale’s innate device that can guide direction C. Whale’s blow hole that allows it to breathe in and out D. Whale’s young baby that cannot travel alone 4. What can be inferred from the passage? A. Pilot whales usually travel in small family groups B. Whales are animals with feelings and sympathy C. The cause of stranding is fully known to scientists D. Whales often survive stranding with the help of human 5．What is the story mainly about? A．How human activity has affected whales. B．What might cause whale strandings. C．How whales find their direction while traveling. D．What scientists are doing to save stranded whales B A UK man who had spent around £300 on vet bills after his pet dog started limping（跛行）, learned that there was nothing wrong with the animal, and it’s said that he was only limping out of sympathy（同情） for him. Russell Jones was left unable to walk without limping after breaking his ankle in an accident last year. One day, while out on a walk with his dog Billy, Russell noticed that Billy was limping as well. So they called a vet to have the dog checked out. After paying around £ 300 ($410) for X-rays and checkups, he learned that Billy was only imitating his behaviour out of sympathy. The London-based couple became even more suspicious (怀疑的) after seeing Billy running free around the garden when Russell wasn't around. A video of Russell and Billy both limping during a walk has gone vir (走红) on social media, with most viewers expressing their amazement at the dog's acting skills. “He's copying you. That's amazing! Though you have my sympathy for the vet's bill,”one person commented. “He’s come out in sympathy with you! Speedy recovery (早日康复) to both of you,” someone else wrote. Although some have expressed doubt that Billy was just imitating his human master, and said that there might have been something wrong with his foot that the X-ray didn't catch, a 2011 study found evidence (证据) of “automatic (自动) imitation” in dogs. Scientists found that dogs will imitate their owners even when it is not in their best interest to do so. 1.What happened to the dog Billy? A. He was limping as his owner Russell Jones did. B. He showed his sympathy for his owner by licking (舔) him. C. He didn't feel well and was taken to the vet. D. He ran free around the garden with his owner. 2.The underlined word "imitating" may probably mean " A.improving B.copying C.stopping D.practicing 3.The viewers felt after watching the video of Russell and Billy both limping during a walk. A.bored B.sad C.nervous D.surprised 4. Which of the following is TRUE according to the passage? A. Russell and Billy were both limping after an accident last year. B. The vet found something wrong with Billy's foot finally. C. The dog was only limping out of sympathy for his owner. D. No one knows why dogs imitate their owners. 5. In which programme can we probably see this story? A. Wild China B. Human and Nature C. Discovery D. Old Friends C ① As man’s best friend, dogs are quite popular in France. From big Great Danes (大丹犬) to little Yorkies (约克犬), French people bring their dogs everywhere, including places like the pharmacy (药店) and the cafe.  ② But it has created a sticky (棘手的) situation for the country. “Dog messes can be a real trouble in some towns, and this ends up making the dogs and their owners look bad,” Loic Dombreval, a member of the French parliament (议会) who specializes in animal issues, told AFP. ③ According to Liberation newspaper, at the end of the 20th century, there were 20,000 kilograms of dog poop on the sidewalks in Paris every year. Each year, about 650 people are sent to the hospital after accidentally stepping in dog poop and slipping. With such conditions, France got a bad reputation (名声) for its poop in public places, noted the Global Times. As a result, many countries were against France’s bid (申请) to hold the 2008 Olympic Games. ④ To ensure cleanliness and good public hygiene (卫生), local French governments have taken measures.  ⑤ Recently, Bergerac, the capital of a popular tourist region in southwestern France, announced (宣布) that dog owners should take at least two collection bags when walking their dogs. The bags would even be given out for free. If owners don’t pick up their dog’s poop immediately, they will be fined (被罚款) up to 750 euros (about 5,300 yuan). That’s probably the highest fine in the country, noted The Brussels Times.  1. What exactly is the “Dog messes” mentioned in Para. 2? A. Too much dog poop being on the streets B. Too many people abandoning their dogs C. Dogs not having enough shelters or food D. Dog owners not cleaning their dogs 2. According to the passage, why were many countries against French’s bid to hold the 2008 Plympics? A. People walking their dogs in public B. Too many people being sent to hospitals C. Few French people caring about dogs D. Poor public hygiene caused by dog poop 3. What is the purpose of paragraph ④? A. To continue the topic of Para. ③ B. To transition into Para. ⑤ C. To start a new topic D. To summarize Para. ①~③ 4. What is the main idea of Para. ⑤? A. Measures to ensure better public hygiene in France B. Why are French people fined for dog poop C. Why people are given collection bags for free D. How to collect dog poop on the streets in France 5. What can be the best title of the passage? A. Keeping Dogs in Paris B. France’s biggest issue C. No Poop, No Doom D. Getting fined in France Unit 7 Unknown World A Stephen Hawking once said that to limit（限制）ourselves to earthly matters would limit the human spirit. We as a species have followed this line of thinking. We’ve achieved great things, including the Moon landing and the Voyager 1 space probe（探测器）launch fifty-three years ago. The Voyager 1 has left our solar system（太阳系）, making it the farthest-traveling spacecraft made by mankind. The year 2019 was a big year for space exploration. NASA’s TESS satellite is searching for worlds beyond our solar system. Scientists successfully took a picture of a black hole for the first time. However, although we have got lots of success, we’re still playing catch-up to the universe’s 13.8 billion years of evolution（演化）. And with every step forward, we find more mysteries. One such mystery was the Oumuamua comet（彗星）in 2017. Unlike other comets, Oumuamua had no tail. It left our solar system quickly. Was Oumuamua just a space rock? Or could it have been an alien probe? We don’t know. Another mystery we have yet to solve has to do with dark matter（暗物质）or dark energy. What are they? We know that they make up over 95 percent of our universe. But we still don’t know how to touch them. Right now, the farthest distance we can see with our space telescopes is 32 billion light years. That’s a great distance, but still very small compared to the size of our universe. How much of the universe have we really discovered? What lies beyond 32 billion light years away? There are still many unanswered questions. But as technology improves, our next discovery might totally change our understanding of our universe. 1. When did the Moon landing and the Voyager 1 space probe launch? A. In 1951. B. In 1965. C. In 1969. D. In 1972. 2. Why the year 2019 was a big year for space exploration? A. Because the Voyager 1 has been launched successfully. B. Because scientists successfully took a picture of a black hole for the first time. C. Because we found all mysteries. D. Because we solved some problems of dark matter. 3. What does the underlined word “It” refer to? A. Oumuamua comet. B. Voyager 1. C. Black hole. D. Dark matter. 4. Which of the following is TRUE? A. We have solved how to do with the dark matter and dark energy. B. 95 percent of the universe is dark energy. C. The farthest distance we can see is 32 billion light years. D. With the development of technology, we may have different understanding of the universe. 5. What is the passage mainly about? A. The Voyager 1 traveled in the solar system. B. The history of space exploration. C. Some information about Oumuamua. D. The universe needs further discovering. B Studying Venus is very difficult because of its thick clouds, which hides the surface. As such, radar（雷达）and other specialist observation techniques（专业观察技术）are needed to study it. Jean-Luc Margot at the University of California and his colleagues studied Venus from 2006 to 2020, using the Goldstone Solar System Radar to hit the planet with radio waves（无线电波）. They then used both this and the Green Bank Telescope some 3000 km away to follow the echoes（回声）of the waves as they bounced back（ 反弹）to Earth. This allowed them to measure very small changes in Venus's movement. They found the planet's day, roughly（粗略地 ）equal to 243 Earth days, changed by up to 21 minutes over the 15 years of observation. “We have a rough estimate（ 估算 ）of about 3500 km for the core’s radius（核心半径）,”says Margot. While the team was unable to know if the core was liquid（ 液体的 ）or solid（固态的）, previous theories（先前的理论）suggests it is mostly made of iron and nickel（ 镍 ）like our own. However, it isn’t known “if Venus has a solid core inside and a liquid core outside, like Earth, or if it's all solid or all liquid”, says Margot. While the estimate is the same as previous models of the core size, having an actual measurable value（实际可测量值）will allow more accurate studies of Venus in the future. Knowing the core’s size and density（密度）is useful in understanding the history of the planet, for example. “It's really difficult to understand anything about a planet unless we have a good picture of its inside,” says Margot. 1. It is hard to study Venus because of its____________. A.size B.distance from the Earth C.thick clouds D.surface 2. By using the Goldstone Solar System Radar and the Green Bank Telescope in the study, Margot learnt the followings EXCEPT A. the radio waves bounced back to Earth B. the small changes in Venus's movement C. how long a day on Venus is D.the form（形态） of Venus’s core 3. A day on Venus is about ____________ days on Earth. A. 3000 B. 243 C. 21 D. 15 4. According to the passage, what is useful in understanding the history of a planet? A. The fossils found on the planet B. The composition (组成) of its atmosphere C. The radius of the planet’s core D. The size and density of the planet’s core 5. What can we learn from the passage? A.With the Goldstone Solar System Radar, scientists can know all about Venus. B. The Green Bank Telescope can make the radio waves. C. The core of Venus is the same as Earth's. D. There is still something of Venus that Margot doesn't understand. C Many people know that rubbish is a big problem on planet Earth. What many people don't know is that junk（垃圾）has become a problem in outer space, too. According to BBC News,there are more than 22,000 pieces of space Junk floating around the earth.And these are just the things that we can see from the surface （ 表面） of the earth by telescopes（望远镜）.There are also millions of smaller pieces of junk that we can't see. Objects （ 物体）, like bits of old space rockets or satellites, move around the planet at very high speed, so fast that even a very small piece can break important satellites or become dangerous to astronauts. If the tiniest piece of junk crashed into a spaceship, it could damage the vehicle（运载工具）. To reduce（减少） additional space junk， countries have agreed that all new space tools can only stay in space for 25 years at most. Each tool must be built to fall safety into the earth's atmosphere after that time. In the upper parts of the atmosphere, it will burn up. Many scientists are also suggesting different ways to clean up space junk. In England, scientists are testing a metal net that can be fired into space junk. The net catches the junk and then pulls it into the earth's atmosphere to burn up. The Germans are building robots that can collect pieces of space junk and bring them back to Earth to be safely destroyed. “The problem is becoming more challenging because we're sending more objects into space to help people use their mobile phones and computers,” says an Italian space researcher. “The time to act is now.The longer we leave the problem, the bigger it will become,” he says. 1.What does the underlined word “these” in Paragraph 2 refer to? A. Telescopes. B. Satellites. C. Pieces of space junk. D. BBC news reports. 2. Why is space junk a problem? A. It burns up after it re-enters the atmosphere. B. It often stops the view of telescopes on Earth. C. It could force new space tools to travel at slower speed. D. It may crash into other space tools causing damage or death. 3.Countries want future space tools to be able to fall back into the earth's atmosphere so that ______________. A.the tools can be reused later B. the tools don't become space junk C. the earths atmosphere can stay clean D.the effects of space flight can be studied 4.How do the Germans plan to deal with space junk? A.Catch it with nets. B. Use robots to collect it. C. Burn it in the earth's atmosphere. D.Send it further away from the earth. 5.In which part of the newspaper would you probably read this article? A. Environment. B. Local News. C. Education. D. Fashion. Unit 8 Life in the Future A In our daily life, robots are often found to do work that is too dangerous, boring, difficult, or dirty. And we often see kids play with toy robots. But what exactly is a robot? There are some important characteristics (特征) that a robot must have. These characteristics might help you to decide what is and what is not a robot. It will also help you to decide what you will need to build into a machine before it can be considered as a robot. A robot has these important characteristics: Sensing First of all, your robot would have to be able to sense the environment around it. Give your robot sensors (传感器): light sensors (eyes), touch sensors (hands), chemical sensors (nose), hearing sensors (ears) and taste sensors (tongue). Movement A robot needs to be able to move around its environment. It can move on wheels, walk on legs or be driven by small engines (发动机). A robot can move either the whole body or just parts of it. Energy A robot needs to be able to power itself. Some robots might power itself with sunlight, some might with electricity, while others with the battery (电池). The way your robot gets its energy will depend on what your robot needs to do. Intelligence A robot needs some kind of "smarts". A programmer is the person who gives the robot its "smarts". The robot will have to have a certain way to receive the program so that is knows what it is to do. 1. The underlined word "it" in Paragraph 2 is about _______________. A. the toy B. the characteristic C. the machine D. the engine 2. The chemical sensors may help a robot to . A. see B. catch C. hear D. smell 3. In how many ways can a robot power itself according to the passage? A. Two. B. Three. C. Four. D. Five. 4. The Chinese meaning of "Intelligence" in the last paragraph is . A. 能源 B. 勤奋 C. 智能 D. 外观 5. What is the main purpose of the passage? A. To help people understand what a robot is. B. To tell what a robot can do in our life. C. To describe the movement of a robot. D. To introduce the history of robots. B If one day you could travel to the moon, what would you bring with you? NASA’s new “lunar backpack” may be a good choice. NASA has developed a “lunar backpack” for future astronauts on the moon. The backpack could give astronauts the ability to create a 3D map of the surface of the moon, according to the Daily Mail. Remote sensing in the backpack uses light detection (检测) and ranging laser (测距激光) light to measure range. It makes use of an innovative type of scanner to provide the range of millions of measurement points (测量点) per second. These measurement points instantly create a real-time navigation system, delivering a 3D high-resolution map of the surrounding terrain (地形), according to NASA. The backpack will ensure the safety of astronauts and rover (探测器) vehicles in the GPS-denied environment of the moon. It can identify distances to far-off landmarks (地标) and show explorers in real time how far they’ve come and how far is left to go to reach their destination, Michael Zanetti, project lead of the backpack, said in a statement. 1. Which of the following is NOT in the “lunar backpack” according to the passage? A. A remote sensing device B. Ranging laser light C. A rover vehicle D. An innovative scanner 2. What can the “lunar backpack” help future astronauts do according to the passgage? A. Create a 3D map of the moon’s surface B. Find ways back to the Earth C. Call for help when astronauts are in danger D. Detect light on the Moon 3. What does the underlined phrase “GPS-denied enviornment” mean in Para. 4? A. An environment fully covered by GPS B. An environment where GPS signal is unstable C. An environment without GPS coverage D. An environment where GPS is blocked (被屏蔽) 4. What is the purpose of the passage? A. To ask astronauts to travel to the moon B. To introduce a new technology for space exploration C. To describe how beautiful the moon is D. To call on scientists to invent new things 5. Where can you most probably find the article? A. In a financial report B. In a newspaper C. In a storybook D. In a science magazine C It is becoming more and more important for scientists to closely monitor（监视）our ocean life. However, it is almost impossible since we will make the animals afraid when we get close to them. Now, thanks to SoFi, the Soft Robotic Fish, scientists may not only be able to keep a close eye on them, but also uncover（揭开） undersea secrets that we haven't known for centuries. Built by MITs Computer Science and Al Lab, the snow white romote-controlled（远程控制的）robot closely emulates real fish，with a soft tail that moves from side to side and two ＂fins＂ （ 鳍 ）. To make sure SoFi can freely move around the ocean and swim like a real fish, a hydraulic pump（水泵）moves water from one balloon-like part to the other through SoFi's soft rubber tail. Robert Katzschmann, a scientist from MITs Computer Science and Al Lab, says, “To our knowledge, this is the first robotic fish that can swim freely in three dimensions（三维）for a long time." During the test in the sea, SoFi swam at the depths of 50 feet for up to 40 minutes at a time, taking photos. Sometimes the fish would swim near the strange-looking robot-fish, while at other times they appeared without noticing it. SoFi now only records videos， the scientists also hope to make it more autonomous（自动的）in the future. "For us, this fish is magical," says Robert. "We imagine someday it might help us uncover more mysteries from the amazing underwater world that we know so little about." 1.The underlined word “emulates” in the passage means “______________” A.观察 B.喂食 C.模仿 D.畅游 2.To make sure SoFi can freely move around the ocean,a hydraulic pump helps it through its A.strange-looking fins B. snow white body C.soft rubber tail D.balloon-like part 3.What can SoFi do in the ocean now? A. It swims with a soft tail that moves up and down. B. It can swim at the depths of 50 feet. C. It is an autonomous robot which now only records sounds. D. It can make some magic for the real fish. 4.We can learn from the passage that SoFi A. often scares the fish when it swims with them B. can watch fish in the ocean without causing any trouble C. is the first robotic fish that can swim in water for days at a time D. swims at a high speed in the ocean 5.The passage is mainly about A. mysteries from the amazing underwater world B. a scientist from MIT's Computer Science and Al Lab C. the Soft Robotic Fish which is remote-controlled D. all the inventions that MIT's Computer Science and Al Lab invented Answer Keys U5 A CDCBA B ABCDA C BDBCD U6 A BABBB B ABDCB C ADBAC U7 A CBADB B CDBDD C CDBBA U8 A CDBCA B CACBD C CCBBC 2 1 学科网（北京）股份有限公司 $$