Ⅴ. 根据短文内容，从短文后的选项中选出能填入空白处的最佳选项。选项中有一项为多余选项。
The Sahara Desert is the largest hot desert in the world. It covers over nine million square kilometres across North Africa. 1. During the day, temperatures rise above $40°\mathrm{C}$, while nights can be very cold. It is one of the toughest environments on earth.
The Sahara Desert is very big but has very few people. Less than two and a half million people live there, most of whom are nomads. Nomads are people who have no permanent（固定的）homes. 2. 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 for them. They need water to live, so they must carry enough water or know where to find it. 3.
A desert is not defined（定义）by sand but by the lack of rain. 4. Surprisingly, only 25% of the Sahara Desert is covered with sand. The rest is rock and gravel（沙砾）.
5. Later it turned into grasslands. Over time, it became the desert we see today. Truly, the Sahara Desert is a place of history and change.
A. Without water, life is impossible.
B. Long ago, the Sahara Desert was covered with forests and lakes.
C. The Sahara Desert is a huge desert full of sand.
D. The weather there can be very different in a day's time.
E. To be a desert, a place must get less than 250 mm of rain each year.
F. They move from place to place, carrying everything they need to live.

1.D 2.F 3.A 4.E 5.B