Description of a DesertIt is difficult to form a correct idea of a desert without having seen one. It is a vast plain of sands and stones, interspersed with mountains of various sizes and heights, usually without roads or shelters. They sometimes have springs of water, which burst forth, and create verdant spots. —————————————————————————————————————————————————————————————————————————————————— Amid the desert, there are springs of water which burst forth and create verdant spots, called oases. There are thirty-two of these that contain fountains, and date and palm trees; twenty of them are inhabited. They serve as stopping places for the caravans, and often contain villages. Were it not for these, no human being could cross this waste of burning sand. So violent, sometimes, is the burning wind that the scorching heat dries up the water of these springs, and then frequently, the most disastrous consequences follow. In 1805, a caravan consisting of 2,000 persons and 1,800 camels, not finding water at the usual resting place, died of thirst, both men and animals. Storms of wind are more terrible in this desert than on the ocean. Vast surges and clouds of red sand are raised and rolled forward, burying everything in its way, and it is said that whole tribes have thus been swallowed up. The situation of such is dreadful, and admits of no resource. Many perish, victims of the most horrible thirst. It is then that the value of a cup of water is truly felt. To be thirsty in a desert, without water, exposed to the burning sun, without shelter, is the most terrible situation that a human being can be placed in, and one of the greatest sufferings that a human being can sustain; the tongue and lips swell; a hollow sound is heard in the ears, which brings on deafness, and the brain appears to grow thick and inflamed. If, unfortunately, any one falls sick on the road, he or she must either endure the fatigue of traveling on a camel, (which is troublesome even to healthy people,) or he or she must be left behind on the sand, without any assistance, and remain so until a slow death comes to relieve him or her.Which of the following could fit the missing paragraph?（）
A.A desert is a barren area of landscape where little precipitation occurs and consequently living conditions are hostile for plant and animal life. The lack of vegetation exposes the unprotected surface of the ground to the processes of denudation. About one third of the land surface of the world is arid or semi-arid. This includes much of the polar regions where little precipitation occurs and which are sometimes called polar deserts or "cold deserts". Deserts can be classified by the amount of precipitation that falls, by the temperature that prevails, by the causes of desertification or by their geographical location. B.Plants and animals living in the desert need special adaptations to survive in the harsh environment. Plants tend to be tough and wiry with small or no leaves, water-resistant cuticles and often spines to deter herbivory. Some annual plants germinate, bloom and die in the course of a few weeks after rainfall while other long-lived plants survive for years and have deep root systems able to tap underground moisture. Animals need to keep cool and find enough food and water to survive. Many are nocturnal and stay in the shade or underground during the heat of the day. They tend to be efficient at conserving water, extracting most of their needs from their food and concentrating their urine. Some animals remain in a state of dormancy for long periods, ready to become active again when the rare rains fall. They then reproduce rapidly while conditions are favorable before returning to dormancy. C.The most remarkable of deserts is the Sahara. This is a vast plain, but a little elevated above the level of the ocean, and covered with sand and gravel, with a mixture of sea shells, and appears like the basin of an evaporated sea. D.Lakes may form in basins where there is sufficient precipitation or meltwater from glaciers above. They are usually shallow and saline, and wind blowing over their surface can cause stress, moving the water over nearby low-lying areas. When the lakes dry up, they leave a crust or hardpan behind. This area of deposited clay, silt or sand is known as a playa. The deserts of North America have more than one hundred playas, many of them relics of Lake Bonneville which covered parts of Utah, Nevada and Idaho during the last ice age when the climate was colder and wetter.正确答案C
