46. What did researchers find puzzling about the first-night effect?
- A. To what extent it can trouble people.
- B. What role it has played in evolution.
- C. What circumstances may trigger it.
- D. In what way it can be beneficial.
答案：D
答案句：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.
参考译文：佐佐木博士知道首夜效应可能与人类进化方式有关。令人困惑的是，当第二天表现可能受到影响时，从中能获得什么好处。
定位线索：题干“puzzling about the first-night effect”→答案句“The puzzle was what benefit would be gained from it”；文中“what benefit would be gained”对应选项D“In what way it can be beneficial”。
解析：题干问研究人员对首夜效应感到困惑的是什么。答案句明确指出“The puzzle was what benefit would be gained from it”，即困惑在于它能带来什么好处，与选项D“In what way it can be beneficial”（它如何有益）同义。选项A“困扰程度”、B“进化中的作用”、C“触发条件”均非文中提到的困惑点，属于无中生有。
47. What do we learn about Dr. Yuka Sasaki doing her research?
- A. She found birds and dolphins remain alert while asleep.
- B. She found birds and dolphins sleep in much the same way.
- C. She got some idea from previous studies on birds and dolphins
- D. She conducted studies on birds' and dolphins' sleeping patterns.
答案：C
答案句：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.
参考译文：她还从先前对鸟类和海豚进行的研究中得知，这些动物一次让一半大脑入睡，以便在休息的同时保持足够警觉以躲避捕食者。这让她想知道人类是否也在做同样的事情。
定位线索：题干“Dr. Yuka Sasaki doing her research”→答案句“previous work conducted on birds and dolphins”；文中“previous work”对应选项C“got some idea from previous studies”。
解析：题干问关于佐佐木博士做研究我们了解到什么。答案句说她“从先前对鸟类和海豚的研究中得知”，这直接对应选项C“她从先前对鸟类和海豚的研究中获得了一些想法”。选项A和B是鸟类和海豚的行为本身，并非关于她的研究；选项D说她进行了鸟类和海豚的研究，但文中明确是“previous work”（先前的工作），并非她所做，属于偷换概念。
48. What did Dr. Sasaki do when she first did her experiment?
- A. She monitored the brain activity of participants sleeping in a new environment.
- B. She recruited 35 participants from her Department of Psychological Sciences.
- C. She studied the differences between the two sides of participants' brains.
- D. She tested her findings about birds and dolphins on human subjects.
答案：A
答案句：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.
参考译文：为了进一步观察，她的团队研究了35名健康人在大学心理科学系陌生环境中睡眠的情况。参与者每人在该系睡了两晚，并通过观察大脑活动的技术被仔细监测。
定位线索：题干“when she first did her experiment”→答案句“studied 35 healthy people as they slept in the unfamiliar environment”；文中“monitored with techniques that looked at the activity of their brains”对应选项A“monitored the brain activity”。
解析：题干问佐佐木博士第一次做实验时做了什么。答案句说她研究了35名健康人在陌生环境中睡眠，并“通过观察大脑活动的技术被仔细监测”，直接对应选项A“她监测了在陌生环境中睡眠的参与者的大脑活动”。选项B说她从心理科学系招募参与者，但文中只说在系里进行，未提及招募来源，属于无中生有；选项C“研究大脑两侧差异”是实验发现而非实验操作；选项D“在人类身上测试鸟类和海豚的发现”是实验目的而非具体操作，且文中未明确表述。
50. What did Dr. Sasaki find about the participants in her experiment?
- A. They tended to enjoy certain tones more than others.
- B. They tended to perceive irregular beeps as a threat.
- C. They felt sleepy when exposed to regular beeps.
- D. They differed in their tolerance of irregular tones.
答案：B
答案句：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.
参考译文：她推断，如果左半球保持警觉以在陌生环境中守卫，那么它会对不规律的蜂鸣声做出反应，将人们从睡眠中唤醒，而忽略规律定时的蜂鸣声。这正是她的发现。
定位线索：题干“find about the participants”→答案句“react to the irregular beeps by stirring people from sleep”；文中“stirring people from sleep”对应选项B“perceive irregular beeps as a threat”。
解析：题干问佐佐木博士关于参与者的发现。答案句说她发现参与者会对不规律蜂鸣声做出反应（被唤醒），而忽略规律蜂鸣声，说明不规律蜂鸣声被视为潜在威胁，对应选项B“他们倾向于将不规律蜂鸣声视为威胁”。选项A“更喜欢某些音调”未提及；选项C“听到规律蜂鸣声感到困倦”与原文“忽略规律蜂鸣声”不符；选项D“对不规则音调的容忍度不同”文中未涉及，属于无中生有。