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问题 填空题

地球的半径约为R=6400千米，A、B两颗人造地球卫星沿圆轨道绕地球运行，它们离地球表面的高度分别为hA=3600千米，hB=1700千米，那末A、B两颗卫星的运行速率之比VA:VB=____________，运行周期之比TA:TB=____________。

答案

9：10；1000：729

单项选择题

铸铁管承接口的对口间隙应小于（）

A.1mm

B.2mm

C.3mm

D.4mm
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单项选择题

Attempts to understand the relationship between social behavior and health have their origin in history. Dubos (1969) suggested that primitive humans were closer to the animals (1) they, too, relied’upon their instincts to stay healthy. Yet some primitive humans (2) a cause and effect relationship between doing certain things and alleviating (3) of a disease or (4) the condition of a wound. (5) there was so much that primitive humans did not (6) the functioning of the body, magic became an integral component ofthe beliefs about the causes and cures of heath (7) Therefore it is not (8) that early humans thought that illness was caused (9) evil spirit. Primitive medicines made from vegetables or animals were invariably used in combination with some form of ritual to (10) harmful spirit from a diseased body.

One of the. earliest (11) in the Western world to formulate principles of health care based upon rational thought and (12) of supernatural phenomena is found in the work of the Greek physician Hippocrates. The writing (13) to him has provided a number of principles underiying modern medical practice. One of his most famous (14) , the Hippocratic Oath, is the foundation of contemporary medical ethics.

Hippocrates also argued that medical knowledge should be derived from a (15) of the natural science and the logic of cause and effect relationships. In this (16) thesis, On Air, Water, and Places, Hippocrates pointed out that human well-being is (17) by the totality of environmental (18) : living habits or lifestyle, climate, geography of the land, and the quality of air, and food. (19) enough, concerns about our health and the quality of air, water, and places are (20) very much written in twentieth century.

3（）

A.symbols

B.signs

C.symptoms

D.syndromes
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