28. What does the author point out at the beginning of the text?
- A. Some mountains are getting higher.
- B. Data on wearables are misleading.
- C. The concept of elevation is relative.
- D. The reference point is hard to locate.
答案：C
答案句：It is common practice to provide the elevation (高度) of a place. Simple readings are now readily available on our phones and wearables. But elevation is necessarily relative: only the choice of a reference point allows us to express numerically the height of an object or a location.
参考译文：提供某个地方的海拔高度是常见做法。现在，简单的读数在我们的手机和可穿戴设备上随时可得。但海拔必然是相对的：只有选择一个参考点，我们才能用数字表达一个物体或地点的海拔高度。
定位线索：题干“at the beginning of the text”→答案句取自第1段“But elevation is necessarily relative”；文中“elevation is necessarily relative”对应选项C“The concept of elevation is relative”（同义转述）。
解析：题干问作者在文章开头指出了什么。答案句第1段先陈述常见做法，然后转折指出“elevation is necessarily relative”，即海拔是相对的，这与选项C“The concept of elevation is relative”直接对应。选项A“一些山变高了”无中生有；选项B“可穿戴设备数据误导”偷换概念，原文只说读数可得，未说误导；选项D“参考点难以定位”与原文“only the choice of a reference point allows us to express numerically”不符，原文强调参考点的必要性而非难度。
29. What is paragraph 3 mainly about?
- A. How the altimeter was invented.
- B. What initiated the author’s research.
- C. Why the digital readings varied.
- D. Where the author spent his holiday.
答案：B
答案句：Appropriately, the book took shape during a summer spent between sea and mountains. A month after visiting the French Riviera and enjoying the sandy beaches of Nice and Menton, I went hiking with friends in the Pala group. Resting on a pass near the Pradidali hut, we began discussing the readings offered by our altimeters (测高仪). Why did they vary ever so slightly from one instrument to the next? This sense of uncertainty led me to think about the meaning of zero. This is how I began my search for the conceptual history of sea level.
参考译文：恰当地说，这本书是在一个穿梭于海洋和山脉之间的夏天成形的。在游览法国里维埃拉并享受尼斯和芒通的沙滩一个月后，我和朋友们去帕拉群峰徒步。在普拉迪达利小屋附近的一个山口休息时，我们开始讨论测高仪给出的读数。为什么它们在不同仪器之间会有细微差异？这种不确定感让我思考零的含义。就这样，我开始探寻海平面的概念史。
定位线索：题干“paragraph 3 mainly about”→答案句取自第3段“This is how I began my search for the conceptual history of sea level”；文中“This is how I began my search”对应选项B“What initiated the author's research”（同义转述）。
解析：题干问第3段主要内容。该段叙述了作者在夏天徒步时因测高仪读数差异而产生疑问，最终“This is how I began my search”，即这开始了他的研究，对应选项B“什么引发了作者的研究”。选项A“测高仪如何发明”无中生有，原文只提到使用测高仪；选项C“数字读数为何不同”是引发研究的契机而非段落主旨；选项D“作者在哪里度假”只是背景细节，不是主旨。
30. What does the underlined word “it” refer to in the last paragraph?
- A. The book.
- B. The project.
- C. The issue.
- D. The development.
答案：C
答案句：Since I began thinking about this project in August 2011, the issue of sea-level rise and the need to place it historically have only become more urgent: between then and the end of 2022 the global sea rose by almost 5 centimeters, about half of the overall rise recorded by satellites since 1993.
参考译文：自从2011年8月开始思考这个项目以来，海平面上升问题以及将其置于历史背景中的必要性变得更加紧迫：从那时到2022年底，全球海平面上升了近5厘米，约占自1993年以来卫星记录的总上升量的一半。
定位线索：题干“the underlined word 'it'”→答案句取自最后一段“the issue of sea-level rise and the need to place it historically”；文中“it”指代前文的“the issue of sea-level rise”，对应选项C“The issue”。
解析：题干问最后一段划线词“it”指代什么。答案句中“the need to place it historically”，“it”紧跟“the issue of sea-level rise”之后，且“place it historically”意为“将其置于历史中”，与“the issue”搭配合理，因此指代“the issue”，对应选项C。选项A“这本书”、B“这个项目”、D“这种发展”均与上下文语境不符，“place it historically”的对象应是“issue”而非其他。
31. What can be the title of the book mentioned in the text?
- A. The Altimeter: A Must-Have
- B. Sea Level: A History
- C. Meaning of Zero: Nothing or Everything
- D. Mountains to Seas: Ups and Downs
答案：B
答案句：In this book, I tell a story of these assumptions. … In this book I examine three crucial stages in the history of mean sea level. These stages mirror the development of human conceptions of the sea.
参考译文：在这本书中，我讲述了这些假设的故事。… 在这本书中，我考察了平均海平面历史上的三个关键阶段。这些阶段反映了人类对海洋观念的发展。
定位线索：题干“title of the book”→答案句取自文中“In this book”相关表述；文中“tell a story of these assumptions”和“examine three crucial stages in the history of mean sea level”对应选项B“Sea Level: A History”；文中“sea level”对应选项“Sea Level”，“history”对应选项“A History”。
解析：题干问书中标题，答案句明确指出本书讲述海平面概念的历史，并考察其历史阶段，因此标题应为“Sea Level: A History”。选项A“The Altimeter: A Must-Have”无中生有，文中未强调测高仪必备；选项C“Meaning of Zero”虽提及但非全书主旨；选项D“Mountains to Seas”范围扩大，文中重点在海平面而非山脉与海洋的对比。