阅读理解微技能（七）科普说明文阅读理解技巧点拨

阅读理解微技能（七）科普说明文阅读理解技巧点拨（完）
科普说明文是高考英语阅读理解的一种常见体裁，着重考查考生对于语篇的理解能力以及信息处理能力，近几年全国卷和各地自主命题卷均涉及这类文章。因此，准确把握此类文章的选材、命题特点、掌握相应的阅读策略与解题技巧对于考生备战高考非常重要。
一、选材特点、文体特征和命题特点
高考英语阅读理解科普类文章思想性和时代感强，题材涉及发明创造、科技创新、科技与生活、科学研究等。文章体裁一般为说明文，语篇主要来源于英美主流报纸、杂志和网站，文章的遣词造句地道，思维逻辑独具英语语言的特点。这些文章和题目不仅能让考生体会到科学的无限趣味和实际功用，而且促使考生深入思考科技创新在人类生活和发展过程中起到的重要作用。
科普类文章的理论性和逻辑性强、篇幅长、生词多、句式结构复杂。文本结构一般包括五个部分：标题（headline）、导语（introduction）、背景（background）、主干（main body）和结尾（ending）。标题高度精辟地概括文章中心思想。高考中科普类阅读理解一般不给标题，反而经常要求考生选择最佳标题。导语一般位于整篇文章的首段。背景则交代研究的起因或者问题现状。主干部分介绍研究所取得的突破，作者往往会详细介绍研究的理论构架、研究对象、研究方法、具体的实验、统计等过程。结尾通常会再次对中心进行概括、重述研究成果、后续研究的方向等，与导语相呼应。
从近年全国卷和各地高考试卷中科普类阅读命题的统计来看，高考阅读理解六种命题类型都有所体现。命题尊重语篇的文体特征和行文特点，考查了考生理解说明文语篇的能力，以及灵活运用各种阅读策略提取、归纳所读信息的能力，尤其加大了对概括能力和推断能力等高阶思维能力的考查。
二、阅读策略和解题技巧
任何一种阅读方法或技巧的使用，都是由语篇特点和试题本身的要求决定的，考生应根据不同的体裁和试题要求采取不同的策略。下面向同学们介绍在解科普类阅读理解题目时常用的阅读策略和解题技巧。
1. 运用语篇结构（text structure），概括全文主旨大意，明晰写作意图。
科普说明文主题鲜明、脉络清晰，行文结构模式较为固定。弄清文本结构有助于把握文章主旨和阅读重点。高考科普类说明文一般分为两种类型：实验研究型和介绍说明型。除了遵循上述文本结构的几个部分的模式外，作者在谋篇布局上常使用以下说明方法：描述法（description）（包括举例子、下定义、列数据等）、因果法（cause and effect）、问题与对策法（problem and solution）。
实验研究型文章一般会以实验的过程进展为线索，多用描述法、问题与对策法等方法，通过列数据、做对比等来说明新的科学研究发现及其产生的影响。介绍说明型文章通常是介绍一种新产品、新技术，更多运用描述法从功能、用途、材料和市场前景等方面进行介绍。
同学们在阅读时，首先用略读法快速浏览每段的首尾句，分析原文的文本结构，然后根据作者谋篇布局的逻辑线索归纳主旨大意。如果文章中含有标题、副标题、图片等，在概括全文主旨大意和写作目的时需要重点考虑。根据英语说明文思维模式特征，作者一般都会开门见山，直奔主题。结尾通常也是中心思想的概括，并与导语相呼应。因此在做主旨大意、写作意图和最佳标题等题目时，需要重点关注首尾段落里面高频复现的词汇和内容。导语、主体和结尾是有机整体，解题时要综合起来进行判断。
2. 利用文中语境线索（context clues），分析长难句，进行逻辑推理判断。
英语文章中有大量的词汇是作者用来联系句子与句子，从而使整篇文章前后贯通、语义明确的。标志词（signal words）就是表明句子间和段落间的逻辑关系、具有词义、语法结构标志作用的词或词组。句子之间的逻辑关系和衔接手段不外乎列举、原因、结果、让步、对照、补充、目的、条件等。如表示列举的连词：for example, for instance；表罗列的连词：first, second, third; to begin with, to conclude；表转折的连词：however, but, whereas；表示原因的连词：because, since, as；表示结果的连词：so, therefore, thus, consequently, as a result；表示对照的连词：on the contrary, by contrast, in comparison；表示目的的连词：so that, in order that等。标志词就像指路牌一样，指明作者思路发展的方向和思路之间的逻辑联系。还有一些出现在术语、抽象概念、长难句前后的同义词、近义词等，都是用以理解文章的语境线索。标志词前后的信息往往都是命题和答题的主要线索或依据，因此，标志词的识别对考生更快更好地理解文章具有举足轻重的作用。
同学们在阅读解题时，第一步可以浏览全文，掌握中心大意。第二步可以根据题干要求，用查读法（scanning）再快速定位到相关段落。第三步可以重点搜索段内的标志词，利用标志词所提供的逻辑关系找到细节信息，如数据、例子、原因和结果等。如果句子成分复杂，有生词，也不要烦躁退缩，分析主句和从句或非谓语动词之间的关系，抓住行文逻辑的标志词，层层剖析，露出主干部分，就能明晰句意，弄懂作者的真实意图。
3. 谙熟选项设置规律，对比原文，去伪存真。
高考作为一种成熟的考试体系，在选项设置上有章可循。掌握一定的规律对甄别正确选项大有帮助。一般说来，正确选项为文中内容的“同义替换”或者“归纳概括”。而干扰项分为“张冠李戴”、“偷梁换柱”、“无中生有”和“以偏概全”四种类型。
“张冠李戴”是命题者把文章作者的观点与他人的观点混淆起来，或者把文中不同地方的信息拼接在一起从而改变了原文的意思。
“偷梁换柱”类型是用了与原文相似的句型结构和大部分相似的词汇，却在不易引人注意的地方换了几个表示程度、限定的词汇，造成句意的改变。
“无中生有”类型往往是生活的基本常识和普遍接受的观点，貌似非常正确，但在原文中并无相关的信息支持，这种选项的设置往往与问题的设问毫不相干。
“以偏概全”则是以局部代替整体，进行不合理关联或者不准确的概括。在下文的例子中，同学们可以更加清楚直观地了解干扰项的特点，在解题时，绕开陷阱，去伪存真。
下面我们结合高考真题对这种题型的解题技巧具体说明。
例1：
As we age, even if we’re healthy, the heart just isn’t as efficient in processing oxygen as it used to be. In most people the first signs show up in their 50s or early 60s. And among people who don’t exercise, the changes can start even sooner.
“Think of a rubber band. In the beginning, it is flexible, but put it in a drawer for 20 years and it will become dry and easily broken,” says Dr. Ben Levine, a heart specialist at the University of Texas. That’s what happens to the heart. Fortunately for those in midlife, Levine is finding that even if you haven’t been an enthusiastic exerciser, getting in shape now may help improve your aging heart.
Levine and his research team selected volunteers aged between 45 and 64 who did not exercise much but were otherwise healthy. Participants were randomly divided into two groups. The first group participated in a program of nonaerobic (无氧) exercise — balance training and weight training — three times a week. The second group did high-intensity aerobic exercise under the guidance of a trainer for four or more days a week. After two years, the second group saw remarkable improvements in heart health.
“We took these 50-year-old hearts and turned the clock back to 30-or 35-year-old hearts,” says Levine. “And the reason they got so much stronger and fitter was that their hearts could now fill a lot better and pump (泵送) a lot more blood during exercise.” But the hearts of those who participated in less intense exercise didn’t change, he says.
“The sweet spot in life to start exercising, if you haven’t already, is in late middle age when the heart still has flexibility,” Levine says. “We put healthy 70-year-olds through a year-long exercise training program, and nothing happened to them at all.”
Dr. Nieca Goldberg, a spokeswoman for the American Heart Association, says Levine’s findings are a great start. But the study was small and needs to be repeated with far larger groups of people to determine exactly which aspects of an exercise routine make the biggest difference.
【阅读思路点拨】
本文是一篇说明文。文章属于实验研究型说明文。文章前两段引出话题，说明随着年龄的增长，心脏也会老化。第二至五段是实验研究的方法、过程和结果，科学家通过研究证实，高强度的有氧锻炼可以提高中老年人心脏的机能。最后一段点明了该项研究的意义、不足之处以及可以进一步研究的方向。
32. What does Levine want to explain by mentioning the rubber band?
A. The right way of exercising.
B. The causes of a heart attack.
C. The difficulty of keeping fit.
D. The aging process of the heart.
【解题技巧点拨】推理判断题。根据第二段中的“‘Think of a rubber band. In the beginning, it is flexible, but put it in a drawer for 20 years and it will become dry and easily broken,’ says Dr. Ben Levine, a heart specialist at the University of Texas. That’s what happens to the heart.（‘想想橡皮筋，一开始它是有弹性的，但把它放在抽屉里20年，它就会变得干燥，很容易断，’得克萨斯大学的心脏专家本·莱文博士说。这就是心脏的变化。）”可知，莱文想通过橡皮筋来解释心脏的老化过程。故选D。B项和C项文中并未提及，都属于“无中生有”。A项提到的锻炼方式，是下文才提及的，并非作者想通过橡皮筋来解释的内容。
33. In which aspect were the two groups different in terms of research design?
A. Diet plan.    B. Professional background.
C. Exercise type.    D. Previous physical condition.
【解题技巧点拨】细节理解题。根据第三段中的“The first group participated in a program of nonaerobic (无氧) exercise — balance training and weight training — three times a week. The second group did high-intensity aerobic exercise under the guidance of a trainer for four or more days a week.（第一组每周参加三次无氧运动——平衡训练和重量训练。第二组在教练的指导下每周进行四天或更多的高强度有氧运动。）”可知，两组在研究设计上的不同在于运动类型的不同。故选C。文中并未提及两组实验对象的饮食计划，也未提及他们的专业背景，所以A、B项都属于无中生有。D项在文章第三段开头提及了“Levine and his research team selected volunteers aged between 45 and 64 who did not exercise much but were otherwise healthy.”，但这是两组实验对象的相同之处，并非不同之处，所以也不可选。
34. What does Levine’s research find?
A. Middle-aged hearts get younger with aerobic exercise.
B. High-intensity exercise is more suitable for the young.
C. It is never too late for people to start taking exercise.
D. The more exercise we do, the stronger our hearts get.
【解题技巧点拨】细节理解题。根据第三段中的“The second group did high-intensity aerobic exercise under the guidance of a trainer for four or more days a week. After two years, the second group saw remarkable improvements in heart health.（第二组在教练的指导下每周进行四天或更多的高强度有氧运动。两年后，第二组的心脏健康状况有了显著改善。）”和第四段中的“‘We took these 50-year-old hearts and turned the clock back to 30-or 35-year-old hearts,’ says Levine.（莱文说：‘我们把这些50岁的心脏的时钟拨回到了30岁或35岁。’）”可知，莱文的研究发现了通过有氧运动，中年人的心脏会变得更年轻。故选A。文中并未提及高强度的锻炼是否适合年轻人，且文中的调查研究涉及的是中老年人，因此B项属于“张冠李戴”，不可选。根据倒数第二段内容可知，人到了七十岁的年纪再开始锻炼的话，已经没作用了。由此可推知，C项与文中信息相悖，不可选。D项的意思是“我们做的运动越多，我们的心脏就越强壮。”这句话看似正确，但并不是文中表达的观点，因此不可选。
35. What does Dr. Nieca Goldberg suggest?
A. Making use of the findings.    B. Interviewing the study participants.
C. Conducting further research.    D. Clarifying the purpose of the study.
【解题技巧点拨】推理判断题。根据最后一段中的“But the study was small and needs to be repeated with far larger groups of people to determine exactly which aspects of an exercise routine make the biggest difference.（但这项研究的规模很小，需要在更大的人群中重复进行，以确定日常锻炼的哪些方面会产生最大的影响。）”可知，妮卡·戈德堡博士建议进行进一步的研究。故选C。
例2：
Plastic-Eating Worms
Humans produce more than 300 million tons of plastic every year. Almost half of that winds up in landfills (垃圾填埋场), and up to 12 million tons pollute the oceans. So far there is no effective way to get rid of it, but a new study suggests an answer may lie in the stomachs of some hungry worms.
Researchers in Spain and England recently found that the worms of the greater wax moth can break down polyethylene, which accounts for 40% of plastics. The team left 100 wax worms on a commercial polyethylene shopping bag for 12 hours, and the worms consumed and broke down about 92 milligrams, or almost 3% of it. To confirm that the worms’ chewing alone was not responsible for the polyethylene breakdown, the researchers made some worms into paste (糊状物) and applied it to plastic films. 14 hours later the films had lost 13% of their mass — apparently broken down by enzymes (酶) from the worms’ stomachs. Their findings were published in Current Biology in 2017.
Federica Bertocchini, co-author of the study, says the worms’ ability to break down their everyday food — beeswax — also allows them to break down plastic. “Wax is a complex mixture, but the basic bond in polyethylene, the carbon-carbon bond, is there as well,” she explains. “The wax worm evolved a method or system to break this bond.”
Jennifer DeBruyn, a microbiologist at the University of Tennessee, who was not involved in the study, says it is not surprising that such worms can break down polyethylene. But compared with previous studies, she finds the speed of breaking down in this one exciting. The next step, DeBruyn says, will be to identify the cause of the breakdown. Is it an enzyme produced by the worm itself or by its gut microbes (肠道微生物)?
Bertocchini agrees and hopes her team’s findings might one day help employ the enzyme to break down plastics in landfills. But she expects using the chemical in some kind of industrial process — not simply “millions of worms thrown on top of the plastic.”
【阅读思路点拨】
本文是一篇说明文。文章围绕一种可以降解塑料的大蜡螟虫子展开，它胃中的酶能够降解塑料，这为解决塑料污染问题提供了新方向。文章具有科普类说明文体的典型特征，属于实验研究型。文章有标题和配图，考生在阅读时要把标题的关键词worm和plastic牢记于心。第一段导语点题。第二至四段为主干，分别描述了研究过程、虫子能降解塑料的原理、后续研究的方向。结尾就如何运用这种方法进行展望。题目设置既注重对语篇整体理解的考查，也关注事实性信息的考查。
43. What can we learn about the worms in the study?
A. They take plastics as their everyday food.
B. They are newly evolved creatures.
C. They can consume plastics.
D. They wind up in landfills.
【解题技巧点拨】细节理解题。根据文章第二段中的“The team left 100 wax worms on a commercial polyethylene shopping bag for 12 hours, and the worms consumed and broke down about 92 milligrams, or almost 3% of it.”可知这些虫子可以消耗聚乙烯购物袋，即塑料袋。A选项具有干扰性，根据文章第三段中第一句提到“这种虫子以蜂蜡为日常食物，他们消化蜂蜡的能力使其能够降解塑料。”可判断A项不对，属“偷梁换柱”干扰类型。D选项属于“张冠李戴”干扰类型。故选C。
44. According to Jennifer DeBruyn, the next step of the study is to _________.
A. identify other means of the breakdown
B. find out the source of the enzyme
C. confirm the research findings
D. increase the breakdown speed
【解题技巧点拨】细节理解题。根据题干信息和文中标志词the next step定位文章第四段最后两句话，可推知下一步研究是要找到酶的来源。故选B。
45. It can be inferred from the last paragraph that the chemical might _________.
A. help to raise worms
B. help make plastic bags
C. be used to clean the oceans
D. be produced in factories in future
【解题技巧点拨】推理判断题。根据文章最后一段“But she expects using the chemical in some kind of industrial process — not simply ‘millions of worms thrown on top of the plastic.’”可知研究者希望那些化学物品可以工业化生产，而不是将许多虫子直接扔在塑料上。故选D。
46. What is the main purpose of the passage?
A. To explain a study method on worms.
B. To introduce the diet of a special worm.
C. To present a way to break down plastics.
D. To propose new means to keep eco-balance.
【解题技巧点拨】目的意图题。根据全文中心思想找出作者的写作意图。通过标题和首尾段，可知全篇文章的核心是阐述虫子和降解塑料之间的关系，C选项中a way指的就是文中的worm，它和plastics是全文的研究对象，而break down指出了两者的关联，所以C项概括了全文的写作意图。A选项“以偏概全”，没有包含worms和plastics之间的关系。B和D选项偏离文章中心。故选C。
三、备考建议
同学们要想做好科普类说明文的阅读理解题，首先要掌握这些文章的结构特点和语言特征，运用有效的阅读策略，真正地读懂并理解它。第二，在复习备考时要回归课本中的科普类说明文，研究课文所涉及的话题、篇章结构、长难句语法结构。第三，加强原版科普类文章阅读，如英美国家主流科普类杂志，了解影响我们生活的世界科技创新和突破。长期坚持，既能够积累常见的科普词汇，形成新思维，还能够提高解答这类题型的能力。