《新世纪研究生公共英语教材阅读A》课文.docx

1、新世纪研究生公共英语教材阅读A课文新世纪研究生公共英语教材阅读A课文Unit 3 Ocean of SandFrom The Guardian1. There is more deserts than sun and sand. On these two pages you can find out how plants, animals and people manage to survive in these apparently barren places. 2. All deserts are dry. The hot, sandy places we think of when we

2、 talk about deserts are subtropical deserts. They are found near the Tropics of Cancer and Capricorn where the warm air which rises at the Equator sinks down again, giving a climate of clear skies and very low rainfall. The Sahara is almost one-third the size of Africa, and is nearly as big as the U

3、. S. A. , the fourth largest country. It was not always a desert. Over millions of years it has been convered in ice, sea, forests and grasslands. 3. Desert winds are usually dry. Some deserts are in “rain shadow” areas where the winds have lost what moisture they had crossing high ground. Others ar

4、e in the middle of continents where the winds blowing over them have lost any moisture gained from distant oceans. The Gobi desert in Mongolia in Asia is an example of such an inland desert. The Atacama in northern Chile is the driest desert on Earth. Parts of the desert had no rain for 400 years, f

5、rom 1570 to 1971, and in other parts, rains had never been recordedn. One of the sandiest deserts is the Takla Makan. Sandstorms can whip up the sand as high as 3, 048 m(10. 000 ft). Windblown sand in the Sahara can be so fierce that it will sandblast the point off a car or aeroplane. The temperatur

6、e at night in a hot desert can drop below freezing, to -4(24). During the day, the sand can be as hot as 79(175). Living in a desert climate4. Deserts are difficult places in which to live. During the day they are very hot. In the Libyan Desert in North Africa the temperature on 13 September 1922 re

7、ached 58C in the shade! But desert nights are often cold because clear skies allow heat to escape into the atmosphere. The lack of water caused by low rainfall is bad enough, but rainfall is also highly unpredictable. Years of drought can end in tremendous rainstorms. Many desert areas are bare rock

8、, or are covered with pebbles and gravel. Sand accounts for only about 15 per cent of the earths desert regions. In some deserts, the total rain for the year might fall in only two or three storms. But that is enough for plant seeds to sprout and bloom, turning parts of the desert into carpets of fl

9、owers for a few days. How plants survive 5. Within a few hours of rain falling, thousands of flowering plants will start to appear. Seeds of plants such as the desert dandelion lie in the ground for years waiting for the rain. 6. These plants die as the desert dries out again, leaving their seeds fo

10、r the next rains. Other plants have adapted to the harsh environment by storing water in their leaves, stems or roots. The American saguaro cactus can hold 6 to 8 tones of water. Desert plants often have spreading root systems which extract every drop of moisture from the ground. The roots of the me

11、squite bush can be 20m deep. 7. Plants generally lose water through pores in their leaves. To prevent this, desert plants have small waxy leaves and fewer pores. Many close their pores during the day so they do not lose moisture. To protect themselves against grazing animals, some plants have thorns

12、 or an unpleasant taste. Cacti are protected by their sharp spines. Cacti are found only in American deserts. The tallest are saguaros which can reach 15m (50 ft) tall, weigh 7 tons and live for 200 years. Water is stored in the stem and used in times of drought. Animal life 8. Although deserts seem

13、 empty, few are without animals. Most animals shelter from the daytime heat in holes or burrows. The burrows trap moisture are stay cooler than the ground above. In the cooler evening or at dawn, the animals emerge. 9. Smaller mammals often have large ears. During the day, the animal loses heat thro

14、ugh its ears. In the dark, large warn the animal of unseen dangers. 10. Reptiles venturing out in daytime try to avoid touching the hot sand. The Australian bearded lizard sometimes runs on its hind legs only. The aptly named sidewinder snake only touches the ground in two places. 11. All desert ani

15、mals survive on little water. Many small animals live on the moisture in their food. Larger animals such as the camel can go without water for days, but drink huge amounts when they get the chance. A camel can drink 10 litres of water in a minute. Desert peoples12. Over thought of years, people have

16、 learnt how to survive in Deserts. The San people of the Kalahari desert in southern Africa and the Australian Aborigines hunt animals and gather food plants. They learn traditional skills from older people. 13. On the edges of the desert, nomadic peoples graze flocks of sheep and goats. They are constantly moving to fresher pastures. Nomads such as the Tuareg of the Sahara in North Africa wear loose chothing to protect them sand and heat. Tuareg