Deserts are found where there is little rainfall or where rain for a whole year falls in only a few weeks' time.Ten inches of rain may be enough for many plants to survive(存活)if the rain is spread throughout the year,If it falls,within one or two months and the rest of the year is dry,those plants may die and a desert may form.
Sand begins as tiny pieces of rock that get smaller and smaller as wind and weather wear them down. Sand dunes(沙丘)are formed as winds move the sand across the desert.Bit by bit,the dunes grow over the years,always moving with the winds and changing the shape.Most of them are only a few feet tall, but they can grow to be several hundred feet high.
There is, however, much more to a desert than sand.In the deserts of the southwestern United States, cliffs(悬崖)and deep valleys were formed from thick mud that once lay beneath a sea more than millions of years ago.Over the centuries, the water dried up.Wind,sand,rain,heat and cold all wore away at the remaining rocks.The faces of the desert mountains are always changing-very,very slowly-as these forces of nature continue to work on the rock.
Most deserts have a surprising variety of life.There are plants,animals and insects that:have adapted to life in the desert. During the heat of the day,a visitor may see very few signs of living things,but as the air begins to cool in the evening,the desert comes to life.As the sun begins to rise again in the sky,the desert once again becomes quiet and lonely.
1.Many plants may survive in deserts when _____.
A.the rain is spread out in a year
B.the rain falls only in a few weeks
C.there is little rain in a year
D.it is dry all the year round
2.Sand dunes are formed when _____.
A.sand piles up gradually
B.there is plenty of rain in a year
C.the sea has dried up over the years
D.pieces of rock get smaller
3.The underlined sentence in the third paragraph probably means that in a desert there is _____.
A.too much sand
B.more sand than before
C.nothing except sand
D.something else besides sand
4.It can be learned from the text that in a desert _____.
A.there is no rainfall throughout the year
B.life exists in rough conditions
C.all sand dunes are a few feet high
D.rocks are worn away only by wind and heat
答案
1-4: AADB
考点名称：科教类阅读
科教类阅读的概念：
科教类阅读主要考查考生对书面语篇的整体领悟能力和接受及处理具体信息的能力。试题的取材，密切联系当前我国和世界经济、科技等方面的变化，有关数据的来源真实可信。
科教类文章阅读技巧：
一、材料特点：
这类文章的总体特点是：科技词汇多，句子结构复杂，理论性强，逻辑严谨。具体说来它有以下几个特点：
1、文章中词汇的意义比较单一、稳定、简明，不带感情色彩，具有单一性和准确性的特点。这类文章通常不会出现文学英语中采用的排比、比喻、夸张等修辞手法，一词多义的现象也不多见。
2、句子结构较复杂，语法分析较困难。为了描述一个客观事物，严密地表达自己的思想，作者经常会使用集多种语法现象于一体的长句。
3、常使用被动语态，尤其是一些惯用被动句式。
二、命题特点：
科普类阅读的主要命题形式有事实细节题、词义猜测题、推理判断题以及主旨概括题等，其中推理判断题居多。
三、应对策略：
1、要想做好科普英语阅读理解题，同学们就要注意平时多读科普知识类文章，学习科普知识，积累常见的科普词汇，从根本上提高科普英语的阅读能力。
2、要熟悉科普类文章的结构特点。科普类文章一般由标题(Head line)，导语(Introduction)，背景(Back ground)，主体(Main body)和结尾(End)五部分构成。标题是文章中心思想高度而又精辟的概括，但根据历年的高考情况来看，这类阅读理解材料一般不给标题，而要同学们选择标题。导语一般位于整篇文章的首段。背景交待一个事实的起因。主体则对导语概括的事实进行详细叙述，这一部分命题往往最多，因此，阅读时，同学们要把这部分作为重点。结尾往往也是中心思想的概括，并与导语相呼应，命题者常在此要设计一道推理判断题。
3、在进行推理判断时，同学们一定要以阅读材料所提供的科学事实为依据，同时所得出的结论还应符合基本的科普常识。