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】
做这篇阅读理解时，我们可以按照先读题干标记关键词、再回原文定位匹配信息的思路解题：
1. 第1题询问撒哈拉沙漠的位置，直接带着关键词"Where is the Sahara Desert"回原文第一段找对应描述，就能快速锁定答案；
2. 第2题判断关于贝都因人的正确表述，带着关键词"Bedouin"回原文第二段定位所有相关内容，逐一和选项比对排除错误项；
3. 第3题询问沙漠的定义，带着关键词"what is a desert"回第三段找定义的描述，直接匹配正确选项；
4. 第4题是主旨题，梳理全文各段落的核心内容，排除只覆盖单个段落的片面选项，选出能概括全文的答案。
【解析】
1. 定位原文第一段第二句"It covers over nine million square kilometres across North Africa"，可知撒哈拉沙漠分布在北非，对应选项B，排除A（北亚）、C（加拿大北部）、D（北美）的错误表述。
2. 定位原文第二段内容逐一比对选项：A选项错误，原文说明Bedouin意为"desert people"，不是热爱沙漠的人；B选项错误，原文说明他们依靠山羊、绵羊和骆驼作为交通方式，没有提到汽车卡车；C选项正确，原文明确写了"Water is the most important to them"；D选项错误，原文提到没有水生命才无法存续，不是没有羊和骆驼就无法生存，因此选C。
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水量低于250毫米的区域，对应D选项，排除A（游牧民居住的地方不是沙漠定义）、B（不是全年都炎热干燥）、C（撒哈拉仅25%是沙，该表述和沙漠定义无关且错误）。
4. 全文分别介绍了撒哈拉的地理位置、气候特点、居住人群、沙漠定义、演变历史，是对撒哈拉沙漠相关事实的全面介绍，B、C、D都只对应文章的某一个部分，属于片面表述，因此选A。
【答案】
1. B 2. C 3. D 4. A
【知识点】
阅读理解细节定位，主旨大意归纳，说明文信息提取
【点评】
本篇是介绍地理常识的说明类阅读，整体难度偏低，绝大多数题目都可以通过原文直接定位得到答案，仅最后一道主旨题容易误选只覆盖单段内容的干扰项，解题时要注意判断主旨选项是否能涵盖全文所有段落的核心内容，不能以偏概全。
【难度系数】
0.7