11 说明文：机制、结构与客观概要

建议位置：高1·下；原创能力递进，不等同于学校实际学期/人教版单元。只训练书面英语。每个编号计一道练习；编号内小项不重复计数。

学习目标

• 识别说明文中的现象—机制—限制结构
• 理解指代和因果链而非只抓关键词
• 写保留限定条件的客观概要
• 在“环境、资源与能源”语境中区分常用词义、搭配并完成新的书面迁移。

核心讲解

1. 说明文的三个问题

作者解释什么现象？用什么机制解释？结论适用于哪些条件？遇到研究介绍应区分观察结果和原因推测。相关变化不自动证明因果；may、in this trial、under these conditions 等限制语不能在概括时丢掉。

2. 段落功能

首段可提出问题，第二段解释过程，第三段提供比较或实例，末段说明限制/应用。段落主旨不一定是第一句原文；可用“对象+作者对此说什么”概括，而非只写一个主题词。

3. 概要与笔记

笔记可用表格“措施—机制—证据—限制”。概要用完整句整合，不罗列每个细节，不加入自己的建议。用 in contrast 表比较，therefore 表结果，however 表转折；连接词必须与事实关系一致。

主题词汇拓展：环境、资源与能源

下面的词条按本课情境扩展意义与搭配，不是课标完整词表。先把词分成“人/物、行动、性质/关系”三组；同一中文词不保证英语可互换。每条搭配示范本课采用的义项。读完语境再做新增的两项迁移题；能认出词义但不能在句中正确使用时，仍应保留为待复习项。

本课词汇与搭配

阅读材料

Original reading: What a Green Wall Can—and Cannot—Tell Us

A wall covered with plants often feels different from a bare wall on a summer afternoon. Part of the explanation is simple: leaves shade the surface, so it absorbs less direct sunlight. Plants also release water through their leaves. As that water evaporates, it can remove some heat from the surrounding area.

To examine the effect, a student research group compared four planted walls with four bare ones. They selected walls facing the same direction and built from similar materials. For six sunny days, they measured surface temperatures at fixed times. The planted walls were generally cooler in the afternoon, though the size of the difference varied from day to day.

This does not mean that adding plants will reduce indoor temperatures or electricity use by the same amount in every building. The students measured wall surfaces, not energy bills. Their sample was small, and wind, wall thickness and indoor heating or cooling could affect the final result. Rainy days might produce a different pattern.

Green walls may still be useful, but they are not maintenance-free. Plants need suitable supports, enough water and attention when they become diseased. In some places, a simple shade structure may be easier to maintain. A good decision therefore begins not with a photograph of an attractive building, but with a clear question about the problem the design is meant to solve.

主题词汇语境：环境、资源与能源

A resource-efficient building may combine insulation, natural ventilation and solar panels, but each measure needs to suit the climate. Reducing energy consumption is not identical to reducing every environmental impact. Materials require resources throughout their life cycle, and water use also matters in a drought-prone area. Designers therefore examine trade-offs rather than label a product sustainable after checking one feature. A useful explanation states which impact was measured and which effects remain uncertain.

例题解析

例 “Two shaded walls were cooler, but the study lasted only four days.” 可概括为 The short trial suggests that shading can reduce wall temperature under the tested conditions。不能写 Shading always cuts energy use：原句只测墙温、时间短，也没有测用电。

本篇结构示范 文章先提出城市墙体温度，再解释遮阴与蒸腾，随后描述小规模比较，最后限定研究结论。temperatures 是测量指标，不是居民健康结果。

练习

1. What is the main purpose? A. To describe a gardening competition. B. To advertise a plant company. C. To explain possible cooling effects and limits of green walls. D. To prove all cities need identical walls.

2. 用中文列出植物可能降低墙面温度的两条机制。

3. “This” in “This does not mean…” 承接前文的什么观察？作者说不能据此推出什么？

4. 为什么研究者比较相同方向、同类材料的墙？回答需说明控制条件的作用。

5. 以下结论哪些有支持？①实验中覆盖植物的墙面下午更凉；②所有绿墙都降低用电20%；③维护与供水是设计时要考虑的因素。

6. 用55—75个英文词写客观概要，必须保留研究规模/条件限制，不加个人倡议。

7. 【主题词汇·辨义】分别解释：renewable与sustainable为何不完全同义？consumption与emission为何不是同一指标？life cycle为何不只指购买当天？

8. 【主题词汇·迁移】写两句比较两种节能措施，使用whereas/while和trade-off；必须写出一项需核查的当地条件，不虚构数字。