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题型:阅读理解-阅读单选 难度:0.65 引用次数:79 题号:9651030

Could blood shortages become a thing of the past? Bacterial enzymes (W) from the human gut (肠,内脏)turn type A blood into the type universally accepted for transfusions, and do it more efficiently than current methods.

Our blood comes in four main varieties: A, B, AB and O. The red blood cells in each type are similar in shape, but they have different sugars on their surfaces. Red blood cells in type A host a particular set of these sugars, with type B having a different set. AB blood cells carry both A and B sugars and type O cells have none.

These sugars can act as antigens(抗原),causing an immune response. For instance, transfusing type B blood into someone with type A can cause death. That is what makes anyone with type O blood a universal donor: there are none of these antigens. So being able to remove these sugars from A, B and AB type blood would be helpful, effectively making it usable in transfusions for all.

"We knew that those same sugars that are on our red blood cells are also produced on the inside of the gut wall," says Steve Withers at the University of British Columbia, Canada. So he and his colleagues started searching for bacteria in human waste (粪便)that might make enzymes that let them feed on and break down gut wall sugars.

Analyzing bacterial genes, they found a family of enzymes that help gut bacteria harvest the sugars. When the team combined the enzymes with type A blood, the sugars were removed from the blood cells, resulting in type O blood. The process is 30 times more efficient than an existing one involving other enzymes.

The bacterial enzymes will have to go through more safety testing before they can be used in blood for human transfusions, but it is a promising step, says Withers. He presented the work at a meeting of the American Chemical Society in Boston this week.

1. Why is a man with type O blood a universal donor?
A.The similar shape of his red blood cells.
B.No sugars on his red blood cells.
C.Different sugars on the blood cells.
D.Different quantity of his red blood cells.
2. How do researchers remove the sugars from blood cells?
A.By analyzing bacteria genes.
B.By combining the enzymes with blood.
C.By removing the enzymes from the cells.
D.By involving different enzymes in blood.
3. In which column of the newspaper can this passage be read?
A.Fashion and Lifestyle.
B.Finance and Business.
C.Travel and Sports.
D.Medicine and Health.

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阅读理解-阅读单选(约370词) | 适中 (0.65)
名校
文章大意:本文是说明文。文章主要介绍音乐对身体和大脑的积极影响,它可以帮助学生克服学业障碍,进而获得更好的成绩。

【推荐1】A quiet space is often considered essential for achieving the concentration that leads to academic success. But research shows that some students may benefit from breaking the silence with certain kinds of music while they study. Music has a powerful influence on both the body and the brain, in ways that can help students navigate the physical and emotional barriers that come with academic challenges.

One U.S. study compared students who took a test to soft music with those who took the test under silent conditions. The study found that students taking a test to music not only completed more questions within a set time but also answered more questions correctly. Music has been further linked to improvements in memory and recall. Experts have found that when music stimulates mood and motivation, students are able to learn more and to better demonstrate their knowledge.

A bit of mood music affects more than just memory and recall when students hit the books. Music can also relieve stress associated with school. Scientists have learned that music engages the autonomic nervous system, which not only controls the unconscious functions of the body but also influences emotions. So it’s no surprise that researchers from the Group Health Research Institute concluded that certain kinds of background music can be just as effective at reducing stress as a massage. Furthermore, while the brain feels better with music, the body may as well. Research shows that certain types of music can make physical pain feel less intense. What’s more, calming music with a steady, meditative (冥想的) rhythm can help people sleep longer and more deeply.

However, some educators express concern that listening to music while trying to concentrate may do more harm than good. Loud music may have a negative influence on a student’s mood or act as a distraction. Actually, the best approach may depend on the students themselves. Listening to music during study time may not mean a guaranteed A for all students, but those who find it helpful should be allowed to plug in their headphones.

1. What does the underlined word “navigate” in the first paragraph probably mean?
A.Recognize.B.Assess.C.Overcome.D.Create.
2. The author writes Paragraph 3 mainly to ________.
A.present the effects of music on mind and body
B.compare the functions of different types of music
C.confirm the impacts of music on memory and recall
D.give examples of the influences of music on emotions
3. What can we learn from this passage?
A.Music helps students remove physical pain immediately.
B.Loud music has the same calming effect as a massage.
C.Listening to music makes it easier for students to multitask.
D.Music is likely to better students’ academic performance.
4. Which of the following would be the best title for this passage?
A.The Power of SilenceB.The Score to Better Scores
C.Music to a Sharper MindD.Road to Academic Success
2022-04-10更新 | 106次组卷
阅读理解-阅读单选(约350词) | 适中 (0.65)
文章大意:这是一篇说明文。文章讲述了科学家们发现了更多的证据,证明海豚会互相称呼对方的“名字”。

【推荐2】Scientists have found further evidence that dolphins call each other by "name".

Research has revealed that the marine mammals use a unique whistle to identify each other. A team from the University of St-Andrews in Scotland found that when the animals hear their own call played back to them, they respond.

Dr. Vincent Janik, from the university's Sea Mammal Research Unit, said, "Dolphins live in this three-dimensional (三维) environment, offshore without any kind of landmarks and they need to stay together as a group. These animals live in an environment where they need a very efficient system to stay in touch. "

It had been long suspected that dolphins use distinctive whistles in much the same way that humans use names. Previous research found that these calls were used frequently, and dolphins in the same group were able to learn and copy the unusual sounds. But this is the first time that the animals' response to being addressed by their "name" has been studied. To investigate, researchers recorded a group of wild bottlenose dolphins, capturing each animal's signature sound. They then played these calls back using underwater speakers.

“We played signature whistles of animals in the group; we also played other whistles in their repertoire (曲目) and then signature whistles of different populations-animals they had never seen in their lives," explained Dr. Janik.

The researchers found that individuals only responded to their own calls, by sounding their whistles back. The team believes the dolphins are acting like humans: when they hear their names,   they answer.

Dr. Janik said this skill probably came about to help the animals to stick together in a group in their vast underwater habitat. He said, "Most of the time they can't see each other, they can't use smell underwater, which is a very important sense in mamma is tor recognition, and they also don't tend to hang out in one spot, so they don't have nests or burrows that they return to.”

1. How can the marine mammals distinguish their group members?
A.By using a special whistle.B.By using special gestures.
C.By speaking special languages.D.By different means of swimming in the sea.
2. What similarities are there between dolphins and humans?
A.They can answer while being called.
B.They can express their feelings with words.
C.They can perform different whistles.
D.They can live individually or in groups.
3. How do dolphins live better in the underwater habitat?
A.See each other clearly.
B.Use the smell underwater.
C.Have nests and get back regularly.
D.Call each other by name and make response.
4. What topic is the passage most related to?
A.Protecting natural environment.
B.The scientific discoveries.
C.The development of scientific technology.
D.The harmonious relationship between man and animals.
2022-02-24更新 | 54次组卷
阅读理解-阅读单选(约330词) | 适中 (0.65)

【推荐3】What are dreams for? A handful of theories have the most influence. Sigmund Freud famously claimed that they reveal hidden truths and wishes. Despite being largely unsupported by evidence,researchers found that students in the U.S.,South Korea,and India were much more likely to accept the view. In the same study,respondents said that dreaming about a plane crash would cause them more anxiety than an official warning about a terrorist attack. More recent research suggests that they may help us process intense emotions,or perhaps sort through and strengthen memories,or rehearse responses to threatening situations.

Even if dreams can’t foretell the future,they seem to expose our shared fascinations. The majority of dreams occur during REM sleep cycles,of which the average person has four or five a night. A study of Canadian university students found the most common dream topics to be school,falling,being chased,and arriving too late for something.

For all the commonalities dreams exhibit,they vary across time people who grew up watching black-and-white TV are more likely to dream in black and white—and culture. A 1958 study determined that compared with Japanese people,Americans dreamed more about being locked up,losing a loved one,finding money. Japanese people were more likely to dream about school,trying repeatedly to do something,being paralyzed with fear,or “wild,violent beasts.”

If human dreams sound boring,bear in mind that even negative ones can have positive effects. In a study of students taking a French medical—school entrance exam,60 percent of the dreams they had beforehand involved a problem with the exam,such as being late or leaving an answer blank. But those who reported dreams about the exam,even bad ones,did better on it than those who didn’t.

1. What do you know about Freud’s view on dreaming?
A.It will cause people more anxiety.
B.It is already been proved by evidence.
C.It is popular with some American and Asian students.
D.It can reveal the hidden truth and predict the future.
2. According to recent research,dreams may________.
A.make emotions intenseB.help prepare for special situations
C.reduce our memoriesD.help us take notes
3. According to paragraphs 2 and 3,which of the following is true?
A.The average person has four or five sleep cycles a night.
B.Canadian students aren’t worried about being late for schoo1.
C.Americans usually share the same dream topics with Japanese.
D.Films about wild beasts may be widely shown in America in 1958.
4. If you dream that you failed the exam,____________.
A.your dream will come true
B.you will be depressed with fear
C.you are supposed to take it seriously
D.it shows that you care a lot about the exam
2019-05-24更新 | 84次组卷
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