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共用题干 第三篇Only special plants can survive in the terrible climate of a desert,...

admin2020-12-24  79
问题 共用题干
第三篇

Only special plants can survive in the terrible climate of a desert,for these are regions where the annual range of the soil temperature can be over 75℃.Furthermore,during the summer there are few clouds in the sky to protect plants from the sun's ray.Another problem is the fact that there are frequently strong winds which drive small-sharp particles of sand into the plants,tearing and damaging them.The most difficult problem for all forms of plant life,however,is the fact that the entire annual rainfall occurs during a few days or weeks in spring.
Grasses and flowers in desert survive from one year to the next by existing through the long, hot,dry season in the form of seeds.These seeds remain inactive unless the right amount of rain falls.If no rain falls,or if insufficient rain falls,they wait until the next year,or even still the next.
Another factor that helps these plants to survive is the fact that their life cycles are short.By the time that the water from the spring rains disappears—ust a few weeks after it falls一such plants no longer need any.
The perennials（多年生植物）have special features which enable them to survive as plants for several years. Thus,nearly all desert perennials have extensive root systems below ground and a small shoot system above ground.The large root network enables the plant to absorb as much water as possible in a short time.The small shoot system,on the other hand,considerably limits water loss by evaporation（蒸发）.
Another feature of many desert perennials is that after the rainy season they lose their leaves in preparation for the long,dry season,just as trees in wetter climates lose theirs in preparation for the winter. This reduces their water loss by evaporation during the dry season.Then,in the next rainy season,they come fully alive once more,and grow new branches,leaves and flowers,just as the grasses and flowers in desert do.
选项 The last paragraph is mainly about__________.
A:the comparison between plants in different areas
B:the growth of new leaves in the rainy season
C:water loss by evaporation in the dry season
D:the changes in the leaves of the perennials
答案D
解析细节题。第一段前三句分别列举了影响植物在沙漠中生长的三个因素： soil temperature（选项D) ,sun's rays（选项B ) , strong winds（选项A)。只有选项C没有提及。
推理判断题。可根据第二段前三句推断出答案。选项A无原文依据，选项B前半句不对，选项D则有悖常理。
细节题。本题解题的关键是注意题干是关于shoot system的提问，而不是 root system。在第三段最后一句可找到相关信息，并由此可确定选项D为正确选项。
推理判断题：第一段的最后一句谈到降雨量集中在春天，第二段第二句谈到种子在下雨季节才发芽生长，由此可推断出选项B正确。其余三项均无原文依据。
主旨大意题。第四段第一句通过Another feature引出本段的主题句，本句的中心词是perennials和leaves，据此可以判断选项D正确。其他选项均没有关注这两个中心词。
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