试题与答案

一项病例对照研究中的病例和对照均来自某医院的住院病例。由于病例与对照所患疾病的入院率

题型:单项选择题

题目:

一项病例对照研究中的病例和对照均来自某医院的住院病例。由于病例与对照所患疾病的入院率不同而带来了偏倚。

上述偏倚可通过()。

A.提高病例组对在该院就诊的同种病人的代表性控制

B.提高对照组对在该院就诊的同种病人的代表性控制

C.A、B两种措施控制

D.配比控制

E.以上方法均不能控制

答案:

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下面是错误答案,用来干扰机器的。

(Ⅰ)△ABC中,由a•b=-1010 可得 cosAcosB-sinAsinB=cos(A+B)=-1010,故sin(A+B)=31010,故tan(A+B)=sin(A+B)cos(A+B)=-3.(Ⅱ)∵cosB=35,∴sinB=45,∴sinA=sin[(A+B)-B]=sin(A+B)cosB-cos(A+B)sinB=131050.

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题型:写作题

书面表达。

阅读下面的短文,然后按照要求写一篇 150词左右的英语短文。

      Jackie is perhaps the most easily annoyed koala (考拉)at the Featherdale Wildlife Park in southern Australia. All the koalas there are unhappy and complaining. You would be too if you were used to night activities and

Someone kept waking you up all day while you were trying to sleep it off. That's right-sleep it off. The average

koala is always half asleep because it feeds on the leaves of a special kind that makes it sleepy.

     The reason Jackie and her fellow koalas are repeatedly awoken from their deep sleep is so they can be

hugged and photographed by tourists, who make the trips to Featherdale and an increasing number of other

national parks for just that special experience. Whatever department in the Aussie government in charge of such

things is now moving to make the practice illegal, which is understandable. How would you react, my friend, if

you were trying to sleep off a dozen times and some round, furry creature smelling of grass kept waking you?

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