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问题 单项选择题 A4型题

某乡有人口2万人约5000户，欲以户为单位抽其中2000人进行某病的调查。

该研究的抽样比是（）

A.1/20

B.1/10

C.1／5

D.1/2

E.资料不足，不能计算

答案

参考答案：B

单项选择题

In the following essay, each blank has four choices. Choose the best answer and write down on the answer sheet.

It is more and more usual that users of Information Retrieval (IR) systems must face up to response of hundreds or thousands of (1) documents. A significant proportion of them are moreover (2) or redundant. This is a straight consequence of two well - known facts: the incessant growing of documental databases and the lack of ability of most users to define (3) information needs. In such a framework, further effective retrieval techniques are only part of the solution. Interfaces with alternative ways for organizing and (4) the results returned by a (5) would be of great utility assisting users to find relevant documents. Document clustering may play a central role as an effective technique for organizing query results.

4（）

A．seeing

B．searching

C．browsing

D．looking for
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问答题 简答题

机采对茶树生育的影响-发芽密度增加
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