B
The Sahara Desert is the largest hot desert in the world. It is about 9,660,000 square kilometers in size. This is almost the size of the America or China. The desert covers eleven countries in the north of Africa.
The Nile runs through the Sahara Desert all year round. But there are also other rivers running through it seasonally. The geography of the desert includes huge sand dunes and dune fields. Some of the sand dunes are so huge that they can even be over 152 meters high. But there are also other amazing landforms in different parts of the desert.
It is very hot and dry in the Sahara Desert. The temperature there is usually 30℃. However, during the hottest months, the temperature can go over 50℃. Because of the high temperatures and poor conditions of the desert, only a few plants live here, just about 500 kinds. They also play a role in the number of animals. In the driest part of the desert, there are only 70 different kinds of animals.
Today the Sahara's population is around four million. They move from place to place through the desert. Because of this there are many different cultures and languages in this area.
()21. From the first paragraph we can know that the Sahara Desert .
A. is the same as America in size
B. is almost as big as China
C. is about 966 000 square kilometers in size
D. covers eleven countries in the south of Africa
()22. What does the underlined word "They" refer to?
A. High temperatures and poor conditions.
B. Some plants and animals.
C. Huge dunes and dune fields.
D. Languages and culture.
()23. What can't we know about the Sahara Desert?
A. Its size. B. Its landforms.
C. Its temperatures. D. Its future.
()24. What can we learn from the passage?
A. There is no water in the Sahara Desert.
B. Only the Nile goes through the desert.
C. There are only seventy different kinds of plants living there.
D. The Sahara area is rich in culture and language.
()25. Where can we find the passage most probably?
A. In a storybook.
B. In a sports magazine.
C. In a geography book.
D. In a health newspaper.

21.B；22.A；23.D；24.D；25.C

21. 细节理解题。根据第一段“This is almost the size of the America or China.”可知，撒哈拉沙漠几乎和中国一样大。A选项“same as”表述错误；C选项数值与原文不符；D选项“south of Africa”与原文“north of Africa”不符，故选B。
22. 词义猜测题。根据第三段“Because of the high temperatures and poor conditions of the desert, only a few plants live here, just about 500 kinds. They also play a role in the number of animals.”可知，前文提到高温和恶劣环境导致植物种类少，这些因素也会影响动物的数量，所以“They”指代高温和恶劣环境，故选A。
23. 细节理解题。文章第一段介绍了撒哈拉沙漠的面积，第二段介绍了地貌，第三段介绍了温度，全文未提及它的未来，故选D。
24. 细节理解题。A选项：原文提到尼罗河常年流经沙漠，还有季节性河流，并非没有水，错误；B选项：原文提到有其他季节性河流流经沙漠，并非只有尼罗河，错误；C选项：原文提到沙漠里有约500种植物，最干旱地区有70种动物，表述错误；D选项：根据最后一段“there are many different cultures and languages in this area.”可知该地区文化和语言丰富，正确，故选D。
25. 推理判断题。本文是关于撒哈拉沙漠的地理类介绍，最可能出现在地理书中，故选C。