Questions 26 to 30 are based on the following passage.
【真题来源：2017年12月大学英语四级真题（第一套）Part Ⅲ，Section C，第46-50题】
Passage One
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, asexpected, 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.
What did researchers find puzzling about the first-night effect?
此题为细节题。题干关键词为first-night effect，researchers, puzzling。据此定位到第二段第二句“The puzzle was what benefit would be gained from it”，句子大意为：（研究者的）困惑是将会从中获得什么利益、好处。可见，D选项为正确答案，“beneficial”是对原文中“benefit”的同义替换。A选项借第一段第一句“trouble sleeping”干扰，该句是first-night effect的定义，且不在定位范围内；B选项借第二段第一句“how human evolved”干扰，不是puzzle的内容；C选项借第三段第一句的“the surrounding environment”干扰，是实验相关内容，不在定位范围内。
What do we learn about Dr. Yuka Sasaki doing her research?
此题为推理题。题干关键词为Dr. Yuka Sasaki doing her research，因关键词为全文话题，定位价值不大，所以可用反证法通过选项关键词来定位，选项共同的关键词为birds and dolphins。据此定位到第二段第三句“She also knew from previous work conducted on birds and dolphins…”，句子大意为她可从之前对鸟类和海豚的研究中得出一些成果，这让她想研究人是否也会做同样的事。可见，C选项为正确答案，是对原文的同义替换。A选项的错误在于asleep（熟睡的）与原文“put half of their brains to sleep”（半睡的状态），意思不符；BD选项的错误在于“sleeping way”和“sleeping pattern”表述不够具体、清楚。
What did Dr. Sasaki do when she first did her experiment?
此题为细节题。题干关键词为Dr. Sasaki, first experiment, do（做法）。“first experiment”在原文中没有原词复现，但根据句意，可知定位处在第二段第四句“this led her to wonder if people might be doing the same thing”后。根据后面原文 “The participants … monitored with techniques that looked at the activity of their brains. ”可知，A选项为正确答案。B选项将原文的“35 healthy people”和“Department of Psychological Sciences”杂糅； C选项的错误在于原文并没有分析大脑的两半的区别；D选项是研究的目的，而非实验中的做法，答非所问。
What did Dr. Sasaki do when re-running her experiment?
此题为细节题。题干关键词为Dr. Sasaki和re-runing her experiment。据此定位到第三段第一句话后半段“while presenting the sleeping participants with a mix of regularly timed beeps of the same and irreugular beeps of a different tone” , C选项是对该句的概括，符合文意。A选项的错误在于干扰睡眠的是irregular beeps, 而非irregular tones；B选项的错误在于没有提及记录实验参与者对变化环境的适应；D选项的错误在于原文未提及不同的实验参与者。
What did Dr. Sasaki find about the participants in her experiment?
此题为细节题。题干关键词为Dr. Sasaki, the participants, find（研究结果）。据此定位到“she worked out that…”后，根据“it would react to the irregular beeps by stirring people from sleep”可知不规律的蜂鸣声会扰乱睡眠，B选项符合文意。A选项的错误在于原文并没有说tones对睡眠有影响；C选项的错误在于sleepy（困乏的），无中生有；D选项的错误在于原文并未提及不同的人对不规律的音调的容忍度不同。