A
A rainforest is an area covered by tall trees with the total high rainfall spreading quite equally through the year and the temperature rarely dipping below l6℃. Rainforests have a great effect on the world environment because they can take in heat from the sun and adjust the climate. Without the forest cover，these areas would reflect more heat into the atmosphere，warming the rest of the world. Losing the rainforests may also influence wind and rainfall patterns，potentially causing certain natural disasters all over the world.
In the past hundred years，humans have begun destroying rainforests in search of three major resources（资源）：land for crops，wood for paper and other products，land for raising farm animals. This action affects the environment as a whole. For example，a lot of carbon dioxide（二氧化碳）in the air comes from burning the rainforests. People obviously have a need for the resources we gain from cutting trees but we will suffer much more than we will benefit.There are two main reasons for this. Firstly，when people cut down trees，generally they can only use the land for a year or two. Secondly，cutting large sections of rainforests may provide a good supply of wood right now，but in the long run it actually reduces the world’s wood supply.
Rainforests are often called the world’s drug store. More than 25％ of the medicines we use today come from plants in rainforests. However，fewer than l％of rainforest plants have been examined for their medical value. It is extremely likely that our best chance to cure diseases lies somewhere in the world’s shrinking rainforests.
1.Rainforests can help to adjust the climate because they
A. reflect more heat into the atmosphere
B. bring about high rainfall throughout the world
C. rarely cause the temperature to drop lower than l6℃
D. reduce the effect of heat from the sun on the earth
2. What does the word “this” underlined in the third paragraph refer to?
A. We will lose much more than we can gain.
B. Humans have begun destroying rainforests.
C. People have a strong desire for resources.
D. Much carbon dioxide comes from burning rainforests.
3. It can be inferred from the text that
A. we can get enough resources without rainforests
B. there is great medicine potential in rainforests
C. we will grow fewer kinds of crops in the gained land
D. the level of annual rainfall affects wind patterns
4. What might be the best title for the text?
A. How to Save Rainforests
B. How to Protect Nature
C. Rainforests and the Environment
D. Rainforests and Medical Development
【答案】1. D 2. A 3. B 4. C
【解析】
试题分析：本文叙述了热带雨林在人们生活中的重要作用，它们能吸收太阳光调节地球上的温度，减少人类得病，还能提供一些药用的植物药材为人类治病，因此，我们要保护热带雨林，不要滥垦滥伐。
【1题详解】
D细节理解题。根据Rainforests have a great effect on the world environment because they can take in heat from the sun and adjust the climate.热带雨林有一个很大的影响对于世界环境,因为他们能吸收来自太阳的热量,调节气候。故选D.
【2题详解】
A词义猜测题。根据People obviously have a need for the resources we gain from cutting trees but we will suffer much more than we will benefit.可知这样会得不偿失，划线词语指代此意，故选A
【3题详解】
B推理判断题。根据More than 25％ of the medicines we use today come from plants in rainforests. However，fewer than l％of rainforest plants have been examined for their medical value. It is extremely likely that our best chance to cure diseases lies somewhere in the world’s shrinking rainforests.热带雨林里有很多的药用植物供我们开采利用，故选B.
【4题详解】
C主旨大意题。根据全篇短文的内容来看主要说的是热带雨林和环境，故选C.
考点：考查环保类短文阅读。
主旨大意题的解题思路与应试技巧
做这类题时常用略读法。快速阅读文章找出各个段落的主题句。把各个段落的主题句联系起来着眼于全文结构安排，了解文章的重心，就能概括出文章的中心。文章的标题是中心思想最精炼的表达形式，选择的标题意义范围要能涵盖全文，不能太大也不能太小。命题者在出这类题时，常常利用生活常识编造干扰项，把文中的细节当主旨，利用局部信息编造干扰项，编制超出文章范围的标题或不能涵盖文章中心意义的标题来考查考生的理解程度，考生要特别留意。
概括主旨的方法是：先看首尾或各段开头再看全文找主题句，若无明显主题句，就通过关键词句来概括(如议论文中寻找表达作者观点态度的词句，记叙文寻找概括情节和中心的动词或反映人物特点的形容词。) 。文中出现两种或两种以上的不同观点时，务必牢记作者的观点才是体现全文中心的。此时，要注意一些转折词，如but, yet, however, although, in spite of, by contrast, on the contrary等。当文章中表示相反的观点时，往往用到这些词。答题时要弄清哪个是作者的观点，排除迷惑性信息，准确归纳主旨大意。
