4 . Babies are surrounded by human language, always listening and processing. Eventually, they put sounds together to produce a “Daddy” or a “Mama”. But what still confuses neuroscientists is exactly how the brain works to put it all together.

To figure it out, a team of researchers turned to a frequent stand-in (代替) for babies when it comes to language learning: the song-learning zebra finch. “We’ve known songbirds learn their song by first forming a memory of their father’s song or another adult’s song. Then they use that memory to guide their song learning,” said Neuroscientist Todd Roberts. “It’s been a long-term goal of the field to figure out how or where in the brain this memory is. This type of imitative learning that birds do is very similar to the type of learning that we engage in regularly—particularly when we’re young, we use it to guide our speech learning.”

Roberts and his team had a feeling that the interface (交叉区域) between sensory areas and motor areas in the brain was critical for this process, and they focused on a group of brain cells called the NIf.

“In order to prove that we could identify these circuits, we thought if we could implant a false memory.” First, they used a virus to cause the neurons (神经元) in the birds’ NIf to become sensitive to light. Then, using a tiny electrode as a flashlight, they activated (激活) the neurons. The length of each pulse of light corresponded with the amount of time the neurons would fire. And the birds’ brains interpreted that time period as the length of each note.

Soon enough, the birds began to practice the notes they had learned, even though they never really heard the sounds. Amazingly, the birds produced them in the correct social situations. The researchers say this is the first time anybody has found exactly a part of the brain necessary for generating the sorts of memories needed to copy sounds.

“This line of research is going to help us identify where in the brain we encode memories of relevant social experiences that we use to guide learning. We know that there are several neurodevelopmental disorders in people that have really far-reaching effects on this type of learning.”

1. The zebra finch is researched because its song-learning mode ________.

A．decides whether it will sing songs

B．helps it to say “Daddy” or “Mama”

C．is like the way babies learn speech

D．reflects its talent for imitating its father’s song

2. What does the underlined word “it” in Paragraph 2 refer to?

A．The interface in the brain.

B．Guidance from adults.

C．Imitative learning type like birds’.

D．The way of regular learning.

3. What can we learn from the research led by Roberts?

A．Scientists activated some neurons by using an electrode.

B．A bird only sings what it heard before.

C．The brain produces tiny electrodes.

D．Birds are sensitive to light.

4. What do the Roberts’ team expect of this line of research?

A．A change in our way of listening and processing.

B．A chance to have relevant social experiences.

C．A better knowledge of the secrets of learning.

D．Identification of neurodevelopmental disorders.

5 . The vaccine (疫苗) news continues to seem very encouraging. Britain started its mass vaccination effort and the U.S. isn’t far behind.

But there is still one dark cloud hanging over the vaccines that many people don’t yet understand.

The vaccines will be much less effective at preventing death and illness in 2021 if they are introduced into a population where the coronavirus is still severe—as is now the case in the U.S.

A vaccine is like a fire hose (消防龙头). A vaccine that’s 95 percent effective, as Moderna’s and Pfizer’s versions appear to be, is a powerful fire hose. But the size of a fire is still a bigger determinant of how much destruction occurs.

At the current level of infection in the U.S. (about 200,000 confirmed new infections per day), a vaccine that is 95 percent effective—distributed at the expected pace—would still leave a terrible toll (伤亡人数) in the six months after it was introduced. Almost 10 million or so Americans would catch the virus, and more than 160,000 would die.

This is far worse than the toll in a different situation where the vaccine was only 50 percent effective but the U.S. had reduced the infection rate to its level in early September (about 35,000 new daily cases). In that case, the death toll in the next six months would be kept to about 60,000.

It’s worth pausing for a moment on this comparison. If the U.S. had maintained its infection rate from September and Moderna and Pfizer had announced this fall that their vaccines were only 50 percent effective, a lot of people would have panicked.

But the reality we have is actually worse.

How could this be? No vaccine can get rid of a pandemic immediately, just as .no fire hose can put out a forest fire. While the vaccine is being distributed, the virus continues to do damage.

There is one positive way to look at this: Measures that reduce the virus’s spread—like mask-wearing, social distancing and rapid-result testing—can still have great consequences. They can save more than 100,000 lives in coming months.

1. How does the author mainly present his argument?

A．By giving definitions.	B．By categorizing facts.
C．By drawing comparisons.	D．By appealing to emotions.

2. Which does the author think is a better way to save lives?

A．Improving the effectiveness of the vaccines.

B．Producing a greater variety of vaccines.

C．Looking at the situation in a positive way.

D．Wearing masks and practicing social distancing.

3. What does paragraph 6 tell us?

A．The vaccines are less effective than expected.

B．The US have controlled the spread of the coronavirus.

C．The death toll in the next six months will be about 60,000.

D．Fewer people will die if the infection rate is lower.

4. What can we infer from the text?

A．The vaccine is the hope of wiping out the pandemic.

B．The public are optimistic about the effects of the vaccine.

C．The public are concerned about the high infection rate.

D．The distribution of vaccine will end the pandemic quickly.

6 . Oxygen, I'm sure you'd agree, is pretty important for life on Earth. We breathe it in, our cells survive on it and without it, we hardly live. Basically all multicellular life on Earth evolved over millions of years to make use of oxygen.

But take a deep breath, because we need to talk about Henneguya salminicola, a tiny parasite(寄生虫) containing fewer than100 cells that lives within the muscle tissue of salmon, a large fish with silver skin and pink flesh. The strange-looking parasite does not busy itself with such small matters as breathing oxygen. Nope, it seems that H. salminicola is the first multicellular animal we've found that survives without the stuff.

“Aerobic respiration(有氧呼吸) was thought to be commonly found in animals, but now we confirmed that this is not the case, "said Dorothee Huchon, a zoologist at Tel Aviv University in Israel, in a press release.

Huchon and a team of international researchers examined and sequenced(排序) all of. salminicola's' genes in their study, published in the journal Proceedings of the National Academy of Sciences. They found that the parasite, which is closely related to jellyfish, lacks the DNA machinery necessary to“breathe”---it doesn't' have mitochondria(线粒体), often called the "powerhouse" of the cell, because they use oxygen to make energy. It's like a little factory inside almost all cells, and DNA detectives can find mitochondrial genes during sequencing.

The discovery came as something of an accident for the team, who were examining the genome (the complete set of genes) of the species. When they went searching for the mitochondrial genes,   they came up empty-handed. "Our discovery shows that evolution can go in strange directions, ”Huchon said. "Aerobic respiration is a major source of energy, and yet we found an animal that gave up this important pathway.”

Some single-celled life forms have evolved the ability to survive without oxygen and do not have mitochondria, either. Plenty of bacteria can exist without oxygen at all. Instead of oxygen, they get their energy from fermentation(发酵) or use other molecules like iron.

But how H. salminicola produces energy is still unclear. Huchon suggests it could draw oxygen from the cells in salmon or it could have evolved similar methods to those of single-celled organisms which scientists have documented in the past.

1. What can we learn about Henneguya salminicola?

A．It is an animal consisting of a cell.

B．It can still survive without oxygen.

C．It takes on a normal appearance.

D．It has a longer lifespan than salmon.

2. What is the main function of mitochondria?

A．To make cells breathe fast.

B．To help to produce oxygen.

C．To provide energy for cells.

D．To help cells absorb oxygen.

3. How did Huchon probably feel about the discovery?

A．Interested.

B．Satisfied.

C．Astonished.

D．Frightened.

4. What could be the most suitable title for the text?

A．The natural evolution of animal cells

B．Different kinds of life forms on earth

C．A research on single-celled organisms

D．A creature that doesn't breathe oxygen

7 . Great work is work that makes a difference in people’s lives, writes David Sturt, Executive Vice President of the O.C. Tanner Institute, in his book Great Work: How to Make a Difference People Love. Sturt insists, however, that great work is not just for surgeons or special-needs educators or the founders of organizations trying to eliminate poverty in sub-Saharan Africa. The central theme of Great Work, according to Sturt, is that anyone can make a difference in any job. It’s not the nature of the job, but what you do with the job that counts. As proof, Sturt tells the story of a remarkable hospital cleaner named Moses.

In a building filled with doctors and nurses doing great life-saving work, Moses the cleaner makes a difference. Whenever he enters a room, especially a room with a sick child, he engages both patients and parents with his optimism and calm, introducing himself to the child and, Sturt writes, speaking “little comments about light and sunshine and making things clean.” He comments on any progress he sees day by day (“you’re sitting up today, that’s good.”) Moses is no doctor and doesn’t pretend to be, but he has witnessed hundreds of sick children recovering from painful surgery, and parents take comfort from his encouraging words. For Matt and Mindi, whose son McKay was born with only half of a heart, Moses became a close friend. As Sturt explains, “Moses took his innate (与生俱来的) talents (his sensitivity) and his practical wisdom (from years of hospital experience) and combined them into a powerful form of patient and family support that changed the critical-care experience for Mindi, Matt and little McKay.”

How do people like Moses do great work when so many people just work? That was the central question raised by Sturt and his team at the O.C. Tanner Institute, a consulting company specialized in employee recognition and rewards system.

O.C. Tanner launched an exhaustive Great Work study that included surveys to 200 senior executives, a further set of surveys to 1,000 managers and employees working on projects, an in-depth qualitative study of 1.7 million accounts of award-winning work (in the form of nominations (提名) for awards from corporations around the world), and one-on-one interviews with 200 difference makers. The results of the study revealed that those who do great work refuse to be defeated by the constraints of their jobs and are especially able to reframe their jobs: they don’t view their jobs as a list of tasks and responsibilities but see their jobs as opportunities to make a difference. No matter, as Moses so ably exemplifies (例证), what that job may be.

1. According to Sturt, which of the following is TRUE?

A．It’s not the nature of the job, but what you do that makes a difference.

B．Anyone in the world is responsible to delete poverty and change the world.

C．Anyone can make a difference in people’s lives no matter what kind of job he does.

D．Surgeons, special-needs educators and founders of organizations can succeed more easily.

2. According to this passage, how does Moses, a common hospital cleaner, make a difference in people’s lives?

A．By keeping optimistic and calm when facing patients and their parents at hospital.

B．By showing his special gift and working experience when working at hospital.

C．By showing his sympathy and kindness to patients when entering their rooms.

D．By pretending to be a doctor or nurse when entering a room with a sick child.

3. The word “constraints” in the last paragraph probably refers to ______.

A．demands

B．advantages

C．disadvantages

D．limitations

4. What can we infer from the passage?

A．Great work is work that makes a difference in people’s lives no matter what you do.

B．If a boss has trouble recognizing his employees, he can ask O. C. Tanner for advice.

C．Moses makes a difference through his sensitivity and his practical wisdom.

D．Those who do great work are never defeated by others or their jobs themselves.

8 . How you talk to yourself about events, experiences and people plays a large role in shaping how you interpret events. When you find yourself interpreting something in a negative way or only focusing on the bad aspect of the situation, look for ways to talk about the events in a more positive light.     1     Instead, it simply means refocusing so that you give fair and equal importance to good events.

When you find yourself worrying about things, look for an uplifting activity to pull yourself out of this negative mindset(心态)     2     In this case, try to turn your attention elsewhere and engage in an activity that brings you joy. Listening to cheerful music, going for a walk, and reading a good book are all ways to get your mind off negative thoughts.

    3     Therefore, it is important to give extra attention to good things that happen. Where negative things might be quickly transferred and stored in your long-term memory, you need to make more efforts to get the same effect from happy moments.     4    Replay the moment several times in your memory and focus on the wonderful feelings the memory inspires.

The negativity bias (偏见) can have a powerful impact on your behavior, but being aware of it means you can take steps to adopt a more positive outlook on life. One of the best ways to combat negative bias is taking a more mindful approach involving being aware of your own tendency toward negativity and consciously elevating (使情绪高昂) happier thoughts to the forefront of awareness.     5    Taking steps to avoid this bias can play a role in boosting your mental well-being.

A．It refers to seeing things in a new view.

B．It takes more for positive things to be remembered.

C．You probably don’t realize how often you say negative things.

D．Thinking repeatedly about the negative can result in a serious loss.

E．So when something great happens, take a moment to really focus on it.

F．This doesn’t mean ignoring potential dangers or wearing rose-colored glasses.

G．For example, you may find yourself mentally reviewing an unpleasant event or outcome.

9 . People have always had to find ways to keep food safe to eat. Methods to dry, smoke and salt food were invented thousands of years ago.     1       This storage method keeps food safe to eat for long periods of time. Today, canning is one of the most popular methods of storing food.

Clean fruits or vegetables are placed in glass bottles. The food can be put into the bottles either hot or cold. The cold method is used for soft fruits and vegetables that could lose their shape or taste.     2       They take up less space in the bottles.

After the food has been placed in glass bottles, boiling water is poured into the bottles to about three centimeters below the top.     3       The bottles are placed in a large container filled with warm water that is then brought to a boil.

The water must completely cover the bottles, from three to five centimeters over the top. When the water boils, any air in the bottles will be expelled. The boiling continues for several minutes. Then the bottles are allowed to cool. Finally, they are placed briefly into cold water.     4       In other words, a vacuum （真空）is created.

When the bottles are completely cool, notes can be placed on them to identify what is inside. The bottles can then be stored in a cool, dark place at a temperature of between 4℃ and 21℃.

    5     It is also a good way to store food for six months to a year, or even several years, in case of an emergency. It does not cost much to continue canning every year once the equipment has been purchased.

A．The process of canning is much more recent.

B．This makes a strong barrier to keep the air out.

C．One popular method of canning uses a water bath.

D．Firmer fruits and most vegetables are usually cooked.

E．Canning uses heat to kill bacteria that cause poisons to form in food.

F．Then covers are placed on the bottles, but they are not turned all the way.

G．Canning allows your family to enjoy foods that might not come fresh throughout the year.

10 . Not too many decades ago it seemed “obvious” both to the general public and to sociologists that modern society has changed people’s natural relations, loosened their responsibilities to kin (亲戚) and neighbors, and substituted in their place superficial relationships with passing acquaintances. However, in recent years a growing body of research   has revealed that the “obvious” is not true. It seems that if you are a city resident, you typically know a smaller proportion of your neighbors than you do if you are a resident of a smaller community. But, for the most part, this fact has few significant consequences. It does not necessarily follow that if you know few of your neighbors you will know no one else.

Even in very large cities, people maintain close social ties within small, private social worlds. Indeed, the number and   quality of   meaningful   relationships   do   not   differ   between more and less urban people. Small-town residents are more involved with kin than are big-city residents. Yet city dwellers compensate by developing friendships with people who share similar interests and activities. Urbanism many produce a different style of life, but the quality of life   does not differ between town and city. Nor are residents of large communities any likelier to display psychological symptoms of stress or alienation, a feeling of not belonging, than are residents of smaller communities. However, city dwellers do worry more about crime, and this leads them to a distrust of strangers.

These findings do not imply that urbanism makes little or no difference. If neighbors are strangers to one another, they are less likely to sweep the sidewalk of an elderly couple living   next door or keep an eye out for young trouble makers. Moreover, as Wirth suggested, there may be a link between a community’s population size and its social heterogeneity (多样性). For instance, sociologists have found much evidence that the size of a community is associated with bad behavior including gambling, drugs, etc. Large-city urbanities are also more likely than their small-town counterparts to have a cosmopolitan(见多识广)outlook, to display less responsibility to traditional kinship roles, to vote for leftist political candidates, and to be tolerant of nontraditional religious groups, unpopular political groups, and so—called undesirables. Everything considered, heterogeneity and unusual behavior seem to be outcomes of large population size.

1. Which of the following statements best describes the organization of the first paragraph?

A．An argument is examined and possible solutions given.

B．Two contrasting views are presented.

C．Research results concerning the quality of urban life are presented in order of time.

D．A detail description of the difference between urban and small-town life is given.

2. According to the passage, it was once a common belief that urban residents .

A．could not develop long-standing relationships.

B．did not have the same interests as their neighbors.

C．tended to be associated with bad behavior.

D．usually had more friends.

3. One of the   consequences   of   urban   life   is   that   impersonal   relationships   among   neighbors .

A．disrupt people’s natural relations.

B．make them worry about crime.

C．cause them no to show concern for one another.

D．cause them to be suspicious of each other.

4. It can be inferred from the passage that the bigger a community is____,

A．the better its quality of life

B．the more tolerant and open-minded it is.

C．the likelier it is to display psychological symptoms of stress.

D．the more similar its interests