重难点03 阅读理解之说明文【命题趋势】最近五年，说明文的出现变化不大，一直很稳定，选材通常是各学科的前沿问题；高科技领域的科研成果；人们比较关心的社会问题；人文方面的经典。由于阅读理解题的设置采用渐进式，即由简到难的方式，因此说明文是高考试卷中阅读理解题中相对比较难的，通常后置。阅读理解试题的中要考点之一是考查学生对词汇和句式的掌握。说明文的词汇和句式的运用较别的体裁的文章难度更大。词汇运用灵活，同一词的不同词性的用法交替出现，未列入考纲的生词较多，通常达到了4-5%。不过考生可以通过说明文的语言特点来帮助理解语篇，例如，下定义、解释、举例、同义词、反义词、上下义词以及标点符号（如破折号、冒号都有表示解释和说明）等。【满分技巧】高考阅读理解中，说明文为主要体裁之一。高考阅读理解题的设问主要围绕以下四方面：细节事实题、主旨大意题、推理判断题、猜测词义题。其中，说明文主要以细节事实、主旨大意和猜测词义三方面问题为主。一、词义猜测类题型阅读理解题中常要求学生猜测某些单词或短语的意思。历年英语高考题中均有此类题目，有的文章尽管没有专门设题，但由于文章中常常出现生词，因此，词义的猜测还是贯穿在文章的阅读理解之中。解这类题目一般是通过上下文去理解或根据构词法去猜测。判断一个单词的意思不但离不开句子，而且还需要把句子放在上下文中，根据上下文提供的线索加以猜测。运用构词法,语境等推测关键词义，可以根据以下几种方法猜测：（一）内在逻辑关系根据内在逻辑关系推测词义是指运用语言知识分析和判断相关信息之间存在的逻辑关系，然后根据逻辑关系推断生词词义。1. 通过同义词和反义词的关系猜词2. 根据因果关系猜测词义3. 通过定义或释义关系来推测词义4. 通过句法功能来推测词义5. 通过描述猜词（二）外部相关因素外部相关因素是指篇章（句子或段落）以外的其他知识，有时仅靠分析篇章内在逻辑关系无法猜出词义。这时，就需要运用生活经验和普通常识确定词义。例如：The snakes lithered through the grass.根据有关蛇的生活习性的知识，我们可以推断出slither词义为爬行。（三）构词法在阅读文章时，我们总会遇上一些新词汇，有时很难根据上下文来推断其词意，而它们对文章的理解又有着举足轻重的作用，此时，如掌握了一些常用的词根,前缀,后缀,合成等构词法知识，这些问题便不难解决了。1. 根据前缀猜测词义2. 根据后缀猜测词义3. 根据复合词的各部分猜测词义二、主旨大意类题型主旨大意类题型主要测试学生对文章全面理解和概括的能力，提问的内容可能是全文的大意，也可能是某段的段落大意，一般不易在文中直接找到答案。怎样把握主旨大意题呢？通常有以下几种方法：（一）阅读文章的标题或副标题文章的标题是一篇文章的题眼，通过阅读标题或副标题可以迅速把握文章的主旨大意。（二）寻找文章的主题句分析篇章结构，找出文章主题。在许多情况下，尤其在阅读说明文和议论文时，根据其篇章特点我们可以通过仔细阅读短文的第一句或第二句，即文章的主题句来归纳出文章的主题.若短文由若干段组成，除仔细阅读第一段的首句外，还须仔细阅读每一段的第一句，即段落中心。通常文章的中心思想包含在文章的首句，有时也在文章的末句，其他句子都是用来说明和阐述主题句。因此，在确定文章的中心思想时，要求学生重视阅读文章的首句和末句。但也有一些文章，中心思想常常贯穿在全文中，因此要求学生综观全文，对段落的内容要融会贯通，对文章透彻理解后归纳总结。主题句的特点是：1. 相对于其他句子，它表达的意思比较概括；2. 主题句一般结构简单；3. 段落中其他句子必定是用来解释，支撑或发展主题句所表达的思想的。【热点话题】 说明文热衷话题有：科普类，环保类。【限时检测】（建议用时：30分钟）A（湖南省长沙市雅礼中学2019届高三下学期一模）话题：新的海洋生态系统难度：建议用时：6分A team of international scientists is due to set off for the worlds biggest iceberg in a mission aiming to answer fundamental questions about the impact of climate change in the polar regions. The scientists, led by the British Antarctic Survey( BAS), are trying to reach a newly revealed ecosystem that had been hidden for 120,000 years below the Larsen C ice shelf.Last year, part of the Larsen C ice shelf calved (崩解) away, forming a huge iceberg-A68-which is four times bigger than London, and revealing life beneath for the first time. Now scientists say it is a race against time to explore these new ecosystems before they are transformed to the light. Marine biologist Dr Katrin Linse from the BAS is leading the mission.“The calving of A68 provides us with a unique opportunity to study marine life as it responds to a huge environment change,” she said. “It is important that we get there quickly before the undersea environment changes as sunlight enters the water.”Professor David Vaughan, science director at the BAs, said, “We need to be bold (大胆的) on this one. Larsen C is a long way south and theres lots of sea ice in the area, but this is important science, so we will try our best to get the team where they need to be. He said climate change had already affected the sea around Antarctica and is warming some coastal waters. “Future warming may make some habitats warm. Where these habitats support unique species that are adapted to love the cold and not the warm, those species are going to either move or die.”There is growing concern about the possible impact of climate change in the Antarctic. Earlier this month, a report revealed that melting ice sheets in Greenland and Antarctica are speeding up the already fast pace of the sea level rise. The research, published by the National Academies of Science, Engineering and Medicine, said, “At the current rate, the worlds ocean will be, on average, at least 60cm higher by the end of the century.” However, it found that the process is accelerating, and more than three quarters of the acceleration since 1993 is due to melting ice sheets in Greenland and Antarctica, the study shows.1. Why are the scientists eager to go to the iceberg?A. To study how the iceberg was formed.B. To study a newly discovered ecosystem.C. To explore a new way to prevent climate change.D. To explore the geography of the Larsen C ice shelf.2. What do the underlined words “this one” in the fourth paragraph refer to?A. The Larsen C ice shelf.B. Climate change in Antarctica.C. The A68 iceberg with the ecosystem beneath it.D. The condition of animal species in Antarctica.3. What can we learn about the A68 iceberg from the text?A. It is as big as London.B. It is part of an ice shelf in the Arctic.C. It will disappear in a very short time.D. It has uncovered an unknown ecosystem in Antarctica.4. What can we infer from the last paragraph?A. There is no need to worry about climate change in Antarctica.B. The ice sheets in Greenland and Antarctica are melting at a steady rate.C. Many creatures living in deep water will die out due to climate change.D. By 2100, the sea level will have risen to a much higher level than now.【文章大意】本文是一篇说明文。南极地区的拉森C冰架崩解形成了一座巨大的冰山A68 iceberg。冰山下面显现的新的海洋生态系