The Sahara

　　The name Sahara derives from the Arabic word for "desert" or "steppe". At 3. 5 million square miles，an area roughly the size of the United States，the Sahara Desert in northern Africa is the largest desert in the world. lt spans the continent from the Atlantic Ocean to the Red Sea. Daytime temperatures can reach as high as 130°F. The humidity sometimes gets into the teens. But it can also be as low as 2. 5 percent，the lowest in the world. Most of the Sahara receives less than five inches of rain per year，while large areas sometimes have no rainfall at all for years.

　　At the heart of the Sahara is the landlocked north African country of Niger. Here the sand

　　dunes can be 100 feet tall and several miles long. Here sand plains stretch over an area larger than Germany where there is neither water nor towns. Yet sitting in the midst of the surrounding desert is the town of Bilma. Suddenly there are pools of cIear water. Surprisingly，there are groves of date palms. Underground water resources，or oases，sufficient to support irrigated agriculture are found in dry stream beds and depressions. Irrigation ditches run off a creek to water fields. Corn，cassava，tea，peanuts，hot peppers，and orange，lime，and grapefruit trees grow in these fields. Donkeys and goats graze on green grass.

　　The Sahara of Niger is still a region where you can see a camel caravan of 500 camels tied together in loose lines as long as a mile，traveling toward such oasis towns. There a caravan will collect life-sustaining salt，which is mined from watery basins，and transport it up to 400 miles back to settlements on the edges of the desert. The round trip across the vast sands takes one month.

　　词汇:

　　Humidity /hju'mId ?t l/ n. 湿度 irrigate / ' lrlgelt/ v. 灌溉

　　stretch / stret?/ v. 伸展 camel /'k m ?l/ n. 骆驼

　　date palms n. 椰枣树

　　注释:

　　1. Underground water resources，or oases，sufficient to support irrigated agriculture are found in dry stream beds and depressions. 在干河床和洼地处可找到充足的地下水资源或者绿洲来支持灌溉农业。

　　2. Irrigation ditches run off a creek to water fields. 灌溉沟渠通过一条小溪到达水田中。

　　3. Donkeys and goats graze on green grass. 青草上放养着驴和山羊。

　　练习:

　　1. This passage is mostly about _______.

　　A) life in the Sahara

　　B) the deserts of Africa

　　C) Bilma

　　D) how camels travel in the desert

　　2. Rainfall in most of the Sahara is_______.

　　A) less than five inches per year

　　B) less than ten inches per year

　　C) less than twenty inches per year

　　D) zero

　　3. The Sahara can be described as_______.

　　A) a place of contrasts

　　B) a place where no one Iives

　　C) an area where the winters are cold

　　D) an area that appeals to many tourists

　　4. The phrase "an area roughly the size of the United States" gives an indication of the size of_______.

　　A) northern Africa

　　B) Niger

　　C) the Sahara

　　D) all of Africa

　　5. In this passage caravan means _______.

　　A) traveling circus

　　B) group traveling together through difficult country

　　C) railroad train

　　D) a small，fast sailing ship

　　答案与题解:

　　1. A 本题问的是:这篇文章主要讲了什么?根据文段，本文主要介绍了撒哈拉沙漠的地理概 况，城镇的农业，以及城镇之间的日常来往。B 选项范围过宽。C 选项不全面，文章不止介绍了比尔马的情况。D 选项文中没有具体介绍。所以 A 是对的。

　　2. A 本题问的是:在撒哈拉的绝大多数地区，降雨情况如何?根据第一段的最后一句话，撒哈拉的绝大多数地区每年降雨量低于 5 英寸。所以 A 正确。

　　3. A 本题问的是:撒哈拉沙漠可以被描述成什么? A 的意思是，一个具有强烈对比的地方。B 的意思是杳无人烟的地方。C 的意思是冬天很冷的地区。D 的意思是吸引很多游客的地方。B，C，D 均不符合文意，因此 A 正确。

　　4. C 本题问的是:句子“大约和美国大小相当的地区”指明的是什么地方的大小?根据第一段的第二句话可知，本句的主语是撒哈拉沙漠。因此 C 正确。

　　5. B 本题问的是:文中“caravan”的意思是什么? A 的意思是旅行马戏团。C 是火车。D 是又小又快的帆船。根据文中的介绍，穿过沙漠的驼队由上百只骆驼组成，来到绿洲城镇收集 盐，因此 B 选项“一群人一起穿过条件恶劣的国家”是正确的。