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问题 选择题

在奥运会举重比赛中，举重选手举着杠铃站着不动，下列符合二力平衡条件的是（　　）

A．杠铃的重力和地面对人的支持力

B．杠铃对人的压力和人对杠铃的举力

C．杠铃的重力和人对杠铃的举力

D．人对地面的压力和地面对人的支持力

答案

A 杠铃的重力受力物体时杠铃而地面对人的支持力的受力物体是人，受力物体不同，不符合“作用在同一物体上的两个力”这一条件，所以不是平衡力．

B、杠铃对人的压力受力物体是人，人队杠铃的举力受力物体是杠铃，受力物体不同，不符合“作用在同一物体上的两个力”这一条件，所以不是平衡力．

C、杠铃的重力和人对杠铃的举力，受力物体都是杠铃，并且两力大小相等、方向相反，所以两力是一对平衡力．

D、人对地面的压力受力物体时地面，地面对人的支持力受力物体时人，受力物体不同，不符合“作用在同一物体上的两个力”这一条件，所以不是平衡力．

故选C．

多项选择题

餐饮产品的质量包括（）。

A.服务质量

B.菜肴质量

C.产品本身的质量

D.外围价值
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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.

8（）

A.surprising

B.obvious

C.promising

D.unwise
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