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【C17】______
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文字出现以后，文化的承传除了口耳相传外，更依赖于文字记载和()。
How many solar heat panels do three or four bedroom homes usually need？
PART C
Directions: You will hear three dialogues or monologues. Before listening to each one, you will have 5 seconds to read each of the questions which accompany it. While listening, answer each question by choosing A, B, C or D. After listening, you will have 10 seconds to check your answer to each question. You will hear each piece ONLY ONCE.
听力原文： Little by little, Americans are turning to solar power, tapping the strength of the sun for energy.
Solar energy is only in its infancy, however, sunlight has already been used for heating or cooling homes and office buildings in the sunny south. Experts say all signs point to the birth of the solar energy industry. Right now, an increasing number of companies are selling solar collector panels to heat and cool homes or to heat water. The glass and metal panels cost from ＄ 100 to more than ＄ 500 each, and the three or four bedroom homes usually require a dozen or more. They look like sandwiches, or very narrow flower boxes, 3 to 6 feet in width, 8 to 10 feet long, and 4 to 8 inches thick. They are usually placed in rooftops. Nobody knows how many have been sold, and in addition, many people have built their own units. It has been estimated that solar power equipment will be a ＄ 1.3 billion industry by 1995, and more a million homes will use sunlight for heat, air conditioning or to generate electricity, both in the cities and in countryside.
What do we learn about the use of solar energy in the USA？
伴有肾功能降低的2型糖尿病的治疗应予
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