2026年考研英语一真题句子解析： The NAFSN sites experienced less than a quarter of the number of fires that would have been expected without fire suppression.

less than (比较结构)

less than

"less than" 是表示数量或程度比较的固定结构,意为"少于、不到"。在本句中修饰 "a quarter",构成 "less than a quarter" (不到四分之一)。这是四六级和考研阅读中的高频比较表达,常用于数据对比和科学论述。需要注意的是,"less than" 后接不可数名词或数字,而 "fewer than" 后接可数名词复数,这是中文学习者容易混淆的点。本句中 "less than a quarter" 将比例作为整体概念,因此用 "less than" 而非 "fewer than"。

• ✓ The sites experienced less than 50% of the expected fires. (比例作为整体概念用 less than) ✗ The sites experienced fewer than 50% of the expected fires. 百分比、分数等比例概念视为不可数,用 less than 而非 fewer than。
• ✓ There were fewer than ten fires. (可数名词复数用 fewer than) ✗ There were less than ten fires. 具体可数的事物用 fewer than。

would have been expected (虚拟语气完成时)

would have been expected

"would have been expected" 是虚拟语气的过去完成时态,表示与过去事实相反的假设。结构为 "would have + 过去分词",此处使用被动语态 "would have been + 过去分词"。本句表达的逻辑是:如果没有灭火措施 (without fire suppression),本应该会发生的火灾数量。这个虚拟条件由 "without" 引入,而非传统的 "if" 从句,是科学写作中常见的简洁表达方式。"would have been expected" 强调这是基于某种预测模型或历史数据得出的理论值,与实际观测值形成对比。

• ✓ Without intervention, the results would have been different. (without 引入虚拟条件,主句用 would have done) ✗ Without intervention, the results would be different. without 表示与过去事实相反时,主句需用 would have done,而非 would do。
• ✓ The number of fires that would have been expected (被动语态,火灾数量是被预期的) ✗ The number of fires that would have expected expect 在此处应为被动,因为是火灾数量被人们预期,而非火灾数量主动预期什么。

a quarter of (分数表达)

a quarter of

"a quarter of" 是表示四分之一的固定分数表达,等同于 "one fourth of" 或 "25% of"。在学术和科技英语中,"a quarter" 比 "one fourth" 更常用且更简洁。该结构后接 "of + 名词" 表示整体的四分之一。本句中 "a quarter of the number" 表示火灾数量的四分之一。需要注意的是,"quarter" 作为分数时是可数名词,可以说 "three quarters",但在 "a quarter" 这个固定表达中,冠词 "a" 是必需的,不能省略。

• ✓ a quarter of the students (冠词 a 不可省略) ✗ quarter of the students 表示四分之一时,"a quarter of" 是固定搭配,冠词 a 必须保留。

the number of (数量表达)

the number of

"the number of" 是表示"……的数量"的固定短语,后接可数名词复数。这个结构本身作为主语时,谓语动词用单数形式,因为主语核心是 "number" (单数概念)。本句中 "the number of fires" 指火灾的数量,作为先行词被后面的定语从句 "that would have been expected" 修饰。中文学习者容易将其与 "a number of" (许多) 混淆:"the number of" 强调数量本身,"a number of" 表示"一些、许多",且后者作主语时谓语用复数。

• ✓ The number of students is increasing. (the number of 作主语,谓语用单数) ✗ The number of students are increasing. the number of 虽然后接复数名词,但整体是单数概念,谓语动词用单数。
• ✓ A number of students are present. (a number of 作主语,谓语用复数) ✗ A number of students is present. a number of 表示"许多",强调复数个体,谓语用复数。

fire suppression (专业术语)

fire suppression

"fire suppression" 是消防和林业管理领域的专业术语,指"灭火、火灾抑制"活动,包括主动扑灭火灾和预防火灾蔓延的措施。这是一个名词复合词,"suppression" 源自动词 "suppress" (压制、抑制)。在科学文献和环境研究中,"fire suppression" 是标准的学术表达,比 "putting out fires" 或 "firefighting" 更正式、更精确。本句讨论的是通过人为干预措施减少火灾发生,因此使用这个专业术语。

without (表示虚拟条件)

without fire suppression

"without" 在本句中不仅表示"没有"这个简单的否定含义,更重要的是引入了一个虚拟条件,相当于 "if there had not been fire suppression" (如果没有灭火措施的话)。这种用法在科学写作和学术论文中非常常见,因为它比完整的 if 从句更简洁。当 "without" 引入与过去事实相反的假设时,主句通常使用 "would have done" 结构,正如本句的 "would have been expected"。这种表达方式体现了科学研究中的对照实验思维:通过比较有干预和无干预两种情况下的结果差异。

• ✓ Without your help, I would have failed. (without 引入虚拟条件,主句用 would have done) ✗ Without your help, I will fail. / Without your help, I would fail. without 表示与过去事实相反的假设时,主句需用 would/could/might have done,不能用 will 或 would do。

对照实验的逻辑表达

The NAFSN sites experienced less than a quarter of the number of fires that would have been expected without fire suppression

本句体现了科学研究中典型的对照实验逻辑表达方式。句子将实际观测值 ("less than a quarter of the number of fires") 与理论对照值 ("would have been expected without fire suppression") 进行对比,以量化干预措施的效果。这种表达结构在科研论文、数据分析报告中极为常见,是学术英语写作的重要模式。关键在于:1) 明确陈述实际情况 (experienced);2) 建立对照基准 (would have been expected);3) 说明对照条件 (without fire suppression);4) 用比较结构 (less than) 量化差异。这种逻辑严密的表达方式是考研英语阅读理解中常见的难点,需要理解虚拟语气、比较结构和科学推理的结合。

比较结构中的省略与指代

less than a quarter of the number of fires that would have been expected

本句的比较结构存在隐含的省略和指代,这是中文学习者的另一个难点。完整的逻辑是:实际发生的火灾数量 (省略了,但由 "experienced" 暗示) 少于 预期火灾数量的四分之一。这里有两个潜在的理解障碍:1) "less than a quarter of the number" 中的 "the number" 指的不是实际火灾数量,而是通过 "that would have been expected" 定语从句所限定的理论预期数量;2) 完整理解需要补全省略:The sites experienced [a number of fires that is] less than a quarter of [the number of fires that would have been expected]。这种省略和指代在科学英语中很常见,是为了表达简洁,但给非母语者造成了理解负担。

• ✓ 实际火灾数量 < (预期火灾数量 × 1/4) ✗ 实际火灾数量的 1/4 < 预期火灾数量 less than a quarter of the number 是指少于该数量的四分之一,不是指自身的四分之一少于该数量。