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问题 单项选择题

对于一种严重的致死性疾病，评价某种一级预防措施的效果时最恰当的指标是（）

A.患病率

B.罹患率

C.发病率

D.病死率

E.死亡率

答案

参考答案：C

解析：此题有两个考点，一为考查流行病学常用指标的应用与区别；二为考查一级预防的含义。一级预防措施为病因预防，病因去除或减少可减少发病。因此，用发病率评价一级预防措施的效果最恰当。

单项选择题

Flying over a desert area in an airplane, two scientists looked down with trained eyes at trees and bushes. After an hour’s flight one of the scientists wrote in his book, "Look here for probable metal. " Scientists in another airplane, flying over a mountain area, sent a message to other scientists on the ground, "Gold possible. " Walking across hilly ground, four scientists reported. "This ground should be searched for metal." From an airplane over a hilly wasteland a scientist sent back by radio one word: "Uranium."
None of the scientists had X-ray eyes: they had on magic powers of looking down below the earth’s surface, They were merely putting to use one of the newest methods of locating minerals in the ground, using trees and plants as signs that certain minerals may lie beneath the ground on which the trees and plants are growing.
This newest method of searching for minerals is based on the fact that minerals deep in the earth may affect the kind of bushes and trees that grow on the surface.
At Weston Bar Greek, a brook six thousand feet high in the mountains of British Columbia, Canada, a mineral search group gathered bags of tree seeds. Boxes were filled with small branches from the trees. Roots were dug and put into boxes. Each bag and box was carefully marked. In a scientific laboratory the parts of the forest trees were burned to ashes and tested. Each small part was examined to learn whether there were minerals in it.
Study of the roots, branches, and seeds showed no silver. But there were small amounts of gold in the roots and a little less gold in the branches and seeds. The seeds growing nearest to the tree trunk had more gold than those growing on the ends of the branches.

Which is the best title suggested below

A．Scientists Searching for Metals with Special Power.
B．New Methods of Searching for Minerals.
C．Gold Could Be Found by Trees and Plants.
D．A New Method of Searching for Minerals—Using Trees and Plants.
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