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问题 单项选择题

下列哪种说法是正确的

A．发病率指观察时期内观察人群中新病例发生的频率

B．罹患率指观察时期观察人群中新旧病例所占的比例

C．患病率指观察时期内观察人群中新病例发生的频率

D．患病率指观察时期内观察人群中旧病例发生的频率

E．发病率指观察时期内观察人群中新旧病例所占的比例

答案

参考答案：A

判断题

动脉硬化病人应避免食用含胆固醇高的食物。
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填空题


Throughout history has (1) changed his physical environment in order to improve his (2) of life. With the tools of technology he has (3) many physical features of the earth. He has (4) woodlands and prairies into farms and made lakes and reservoirs (5) of rivers for irrigation purposes or hydroelectric (6) . Man has also modified the face of the earth by (7) marshes and cutting through mountains to (8) roads and railways.
However, man’s (9) to the physical environment have not always had beneficial results. Today, (10) of the air and water is an increasing danger to the health of the (11) . Each day thousands of tons of gases come out of the exhausts of motor vehicles. (12) from factories pollutes the air of industrialized areas and the surrounding (13) of the countryside. The pollution of water is equally harmful. The whole ecological (14) of the sea is being changed and (15) wastes have already made many rivers lifeless.
Now (16) protection is more pressing than ever before. As we know, massive destruction of the environment has brought about (17) effects and even poses a great (18) to man’s existence. Indifference to these problems will mean committing suicide. Therefore, effective (19) should be taken and laws passed to (20) the environment. Otherwise, man is certain to suffer from the serious consequences caused by this lack of care for his living surroundings.
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