六、阅读理解。
The Sahara Desert is the largest hot - and - dry desert in the world. It covers over nine million square kilometres across North Africa. The weather there can be very different in a day's time. During the day, temperatures rise above 40℃，while it can be very cold at night. It is one of the toughest(艰难的)environments on the earth.
The Sahara Desert is very big but has very few people. About two and a half million people live there. Most of them are nomads. Nomads are people who have no permanent(固定的)homes. They move from place to place, carrying everything they need to live. The nomads of the Sahara Desert are called Bedouin, which means “desert people”. They depend on goats, sheep, and camels for food and transport. Water is the most important to them. They need water to live, so they must carry enough water or know where to find it. Without water, life is impossible.
A desert is not defined(定义)by sand but by the lack of rain. To be a desert, a place must get less than 250 mm of rain each year. Surprisingly, only 25% of the Sahara Desert is covered in sand. The rest is rock and gravel(沙砾).
Long ago, the Sahara Desert was covered in ice and later turned into grasslands. Over time, it became the desert we see today.
()1. Where is the Sahara Desert?
A. In North Asia.
B. In North Africa.
C. In North Canada.
D. In North America.
()2. Which of the following is TRUE about Bedouin?
A. The word “Bedouin” means “people who love deserts”.
B. Bedouin use cars and trucks to get around.
C. The most important thing for Bedouin is water.
D. Life is impossible without goats, sheep or camels for Bedouin.
()3. According to the passage, what is a desert?
A. A place where nomads live.
B. A place where it is very hot and dry all year round.
C. A place that has more than 25% sand on its surface.
D. A place that gets less than 250 mm of rain every year.
()4. What is the passage about?
A. Facts about the Sahara Desert.
B. The people of the Sahara Desert.
C. The weather of the Sahara Desert.
D. The history of the Sahara Desert.

六、1. B 【点拨】根据“The Sahara Desert is the largest hot-and-dry desert in the world. It covers over nine million square kilometres across North Africa.”可知，撒哈拉沙漠位于北非。故选 B。
2. C 【点拨】根据“Water is the most important to them. They need water to live, so they must carry enough water or know where to find it.”可知，对贝都因人来说，最重要的是水。故选 C。
3. D 【点拨】根据“A desert is not defined（定义）by sand but by the lack of rain. To be a desert, a place must get less than 250 mm of rain each year.”可知，沙漠的定义是年降雨量不足 250 毫米。故选 D。
4. A 【点拨】文章详细介绍了撒哈拉沙漠的地理位置、气候特征、居住的游牧民族以及历史变化等内容，全面介绍了撒哈拉沙漠的相关事实。故选 A。

【分析】
这是一篇介绍撒哈拉沙漠的说明类阅读理解，解题时可以先通读题干明确每道题的设问方向，再带着问题回到原文对应段落定位关键信息，将每个选项和原文表述逐一比对，排除和原文不符的错误选项：细节题直接找对应原文语句验证正误，主旨题需要综合全文所有段落的内容，排除只覆盖局部段落的片面选项，最终选出正确答案。
【解析】
1. 定位原文第一段第二句“It covers over nine million square kilometres across North Africa”，可知撒哈拉沙漠位于北非，排除A（北亚）、C（加拿大北部）、D（北美洲）选项，选B。
2. 逐一比对第二段关于贝都因人的描述：A选项“Bedouin意为热爱沙漠的人”和原文“which means "desert people"”不符，错误；B选项“贝都因人靠汽车卡车出行”和原文“They depend on goats, sheep, and camels for food and transport”不符，错误；C选项“对贝都因人来说最重要的是水”和原文“Water is the most important to them”表述完全一致，正确；D选项“没有山羊、绵羊、骆驼贝都因人就无法生存”和原文“Without water, life is impossible”不符，错误。
3. 定位原文第三段“To be a desert, a place must get less than 250 mm of rain each year”，可知沙漠的定义是年降雨量不足250毫米，排除A（游牧民居住的地方）、B（全年炎热干燥的地方）、C（地表沙占比超25%的地方）选项，选D。
4. 全文依次介绍了撒哈拉沙漠的地理位置、气候特征、居住的游牧民族、沙漠的判定标准、撒哈拉的演变历史，所有内容都是撒哈拉沙漠的相关事实，B、C、D选项都只对应文章的某一个局部段落，表述片面，只有A能覆盖全文内容，选A。
【答案】
1. B 2. C 3. D 4. A
【知识点】
阅读理解细节定位，说明文主旨大意，文本信息比对
【点评】
本题属于难度偏低的常识类说明文阅读，绝大多数题目为细节理解题，只要学生能准确定位原文对应语句就能选出正确答案，最后一道主旨题引导学生避免以偏概全的误区，整体可以有效锻炼学生快速从阅读文本中抓取关键信息的能力。
【难度系数】
0.8