以下关于中心极限定理及样本均值的分布说法错误的是() A.随着样本量的无限增长,无论

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问题:

以下关于中心极限定理及样本均值的分布说法错误的是()

A.随着样本量的无限增长,无论原来的分布呈何种形态,样本平均的分布总会趋向于正态分布

B.我们可以利用中心极限定理原则来减少测量系统误差;如果想使测量系统的误差减小一半,我们只要把2次的测量值平均就可以了

C.样本平均值分布的平均值和总体的平均值十分接近

D.样本平均值分布的标准偏差等于总体的标准偏差除以样本数的平方根

考点:六西格玛管理六西格玛管理题库
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肾性高血压最好选用卡托普利。

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茯苓的常用剂量是()

A.6~12g

B.10~15g

C.9~12g

D.6~9g

E.3~6g

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在物料的降速干燥阶段,不正确的表述是

A.物料内部的水分及时补充到物料的表面

B.改变空气状态及流速对干燥速度的影响不大

C.干燥速率主要由受物料内部水分向表面的扩散速率所决定

D.提高物料的温度可以加快干燥速率

E.改善物料的分散程度可以加快干燥速率

题型:单项选择题

Do you know that men die earlier than women? The latest research makes it known that the reason could be that men’s hearts go into rapid decline when they reach middle age.

  The largest study of the effects of ageing(变老) on the heart has found that women’s longevity may be linked to the fact that their hearts do not lose their pumping power with age.

  “We have found that the power of the male heart falls by 20-25 percent between 18 and 70 years of age,” said the head of the study, David Goldspink of Liverpool John Moores University in the UK.

  “Within the heart there are millions of cells that enable it to beat. Between the age of 20 and 70, one-third of those cells die and are not replaced in men,” said Goldspink. “This is part of the aging process.”

  What surprises scientists is that the female heart sees very little loss of these cells. A healthy 70-year-old woman’s heart could perform almost as well as a 20-year-old one’s.

  “This gender difference might just explain why women live longer than men,” said Goldspink. They studied more than 250 healthy men and women between the ages of 18 and 80, focusing on healthy persons to remove the confusing influence of disease. “The team has yet to find why ageing takes a greater loss on the male heart,” said Goldspink.

  The good news is that men can improve the health of their heart with regular exercise. Goldspink stressed that women also need regular exercise to prevent their leg muscles becoming smaller and weaker as they age.

小题1: The underlined word “longevity” in the second paragraph probably refers to “________”.

A.health

B.long life

C.ageing

D.effect小题2: The text mainly talks about ________.

A.men’s heart cells

B.women’s ageing process、

C.the gender difference

D.hearts and long life小题3:According to the text, the UK scientists have known that ________.

A.women have more cells than men when they are born

B.women can replace the cells that enable the heart to beat

C.the female heart loses few of the cells with age

D.women never lose their pumping power with age小题4:If you want to live longer, you should ________.

A.enable your heart to beat much faster

B.find out the reason for ageing

C.exercise regularly to keep your heart healthy

D.prevent your cells from being lost小题5:We can know from the passage that ________.

A.the reason why ageing takes a greater loss on the male heart has been found out

B.scientists are on the way to finding out why the male heart loses more of the cells

C.the team has done something to prevent the male from suffering the greater loss

D.women over 70 could lose more heart cells than those at the age of 20

题型:单项选择题

氢氯噻嗪理化性质和临床应用为( )。

A.利尿药

B.主要是抑制肾小管对钠、氯离子的再吸收而产生利尿作用

C.有降血压作用

D.在水溶液中稳定

E.易溶于水

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