2017 年 12 月大学英语四级考试真题（第 1 套）

Questions __26__ to __35__ are based on the following passage.

A rat or pigeon might not be the obvious choice to tend to someone who is sick, but these creatures have some __26__ skills that could help the treatment of human diseases.

Pigeons are often seen as dirty birds and an urban __27__ , but they are just the latest in a long line of animals that have been found to have abilities to help humans. Despite having a brain no bigger than the __28__ of your index finger, pigeons have a very impressive __29__ memory. Recently it was shown that they could be trained to be as accurate as humans at detecting breast cancer in images.

Rats are often __30__ with spreading disease rather than __31__ it, but this long-tailed animal is highly __32__ . Inside a rat's nose are up to 1,000 different types of olfactory receptors (嗅觉感受器), whereas humans only have 100 to 200 types. This gives rats the ability to detect __33__ smells. As a result, some rats are being put to work to detect TB (肺结核). When the rats detect the smell, they stop and rub their legs to __34__ a sample is infected.

Traditionally, a hundred samples would take lab technicians more than two days to __35__ , but for a rat it takes less than 20 minutes. This rat detection method doesn't rely on specialist equipment. It is also more accurate — the rats are able to find more TB infections and, therefore, save more lives.

That people often experience trouble sleeping in a different bed in unfamiliar surroundings is a phenomenon known as the "first-night" effect. If a person stays in the same room the following night they tend to sleep more soundly. Yuka Sasaki and her colleagues at Brown University set out to investigate the origins of this effect.

Dr. Sasaki knew the first-night effect probably has something to do with how humans evolved. The puzzle was what benefit would be gained from it when performance might be affected the following day. She also knew from previous work conducted on birds and dolphins that these animals put half of their brains to sleep at a time so that they can rest while remaining alert enough to avoid predators (捕食者). This led her to wonder if people might be doing the same thing. To take a closer look, her team studied 35 healthy people as they slept in the unfamiliar environment of the university's Department of Psychological Sciences. The participants each slept in the department for two nights and were carefully monitored with techniques that looked at the activity of their brains. Dr. Sasaki found, as expected, the participants slept less well on their first night than they did on their second, taking more than twice as long to fall asleep and sleeping less overall. During deep sleep, the participants' brains behaved in a similar manner seen in birds and dolphins. On the first night only, the left hemispheres (半球) of their brains did not sleep nearly as deeply as their right hemispheres did.

Curious if the left hemispheres were indeed remaining awake to process information detected in the surrounding environment, Dr. Sasaki re-ran the experiment while presenting the sleeping participants with a mix of regularly timed beeps (蜂鸣声) of the same tone and irregular beeps of a different tone during the night. She worked out that, if the left hemisphere was staying alert to keep guard in a strange environment, then it would react to the irregular beeps by stirring people from sleep and would ignore the regularly timed ones. This is precisely what she found.

It's time to reevaluate how women handle conflict at work. Being overworked or over-committed at home and on the job will not get you where you want to be in life. It will only slow you down and hinder your career goals.

Did you know women are more likely than men to feel exhausted? Nearly twice as many women than men ages 18-44 reported feeling "very tired" or "exhausted", according to a recent study.

This may not be surprising given that this is the age range when women have children. It's also the age range when many women are trying to balance careers and home. One reason women may feel exhausted is that they have a hard time saying "no." Women want to be able to do it all volunteer for school parties or cook delicious meals-and so their answer to any request is often "Yes, I can."

Women struggle to say "no" in the workplace for similar reasons, including the desire to be liked by their colleagues.

Unfortunately, this inability to say "no" may be hurting women's health as well as their career.

At the workplace, men use conflict as a way to position themselves, while women often avoid conflict or strive to be the peacemaker, because they don't want to be viewed as aggressive or disruptive at work. For example, there's a problem that needs to be addressed immediately, resulting in a dispute over who should be the one to fix it. Men are more likely to face that dispute from the perspective of what benefits them most, whereas women may approach the same dispute from the perspective of what's the easiest and quickest way to resolve the problem-even if that means doing the boring work themselves.

This difference in handling conflict could be the deciding factor on who gets promoted to a leadership position and who does not. Leaders have to be able to delegate and manage resources wisely including staff expertise. Shouldering more of the workload may not earn you that promotion. Instead, it may highlight your inability to delegate effectively.