问题 单项选择题

下列说法错误的一项是

A.计算率的分母要有一定数量

B.对样本率的比较要做假设检验

C.对构成比的比较要做假设检验

D.婴儿死亡率不符合率的定义

E.某校男女生近视患病率分别为P1,P2,则合计近视患病率为(P1+ P2)/2

答案

参考答案:E

解析:因为对观察单位数不等的几个率不能直接相加求其平均率。D所以正确。因为婴儿死亡率的分子是某年不满I岁婴儿死亡数,分母是该年活产数,分子中有当年出生,也可能有上一年出生的婴儿。也即分子不是分母的一部分,故其不符合“率”的定义。

多项选择题
阅读理解

Thirty years ago not many people would have dreamed of doing the repairs and decorations in their own homes. In those days labor was fairly cheap and most people would have thought it worthwhile to employ a professional painter and decorator, unless of course they were either very hand up or were in the trade themselves.

Today, however, it is quite a different story. Men and women in all walks of life turn their hands to all sorts of jobs round the house including painting, papering, putting up shelves and wall units, and tiling walls and floors. Some people with no professional training of any kind have even successfully built their own houses. These jobs have been made easier today by the introduction of prepared materials, which require the minimum amount of skill to use. In every high street throughout Britain nowadays there is at least one “Do-It-Yourself” shop containing a vast range of timber, tiles, paints, wallpapers and floor coverings besides tools of every description including power drills and many accessories. “Do-It-Yourself” is a booming business; all these shops do a roaring trade and look like continuing to do so. Probably the main reason for the craze is the high cost of present-day labor and the shortage of building firms willing to do small jobs.

小题1:Why did people employ professional workers to decorate homes thirty years ago?

A.Because they could not do it themselves.

B.Because professional workers were very cheap.

C.Because they had no time.

D.Because professional workers could do much better.小题2:Thirty years later what changes took place?

A.People could do everything themselves.

B.Few people chose to be a professional worker.

C.People with no professional training successfully built their own houses.

D.New expensive materials required no skills at all.小题3:What caused the DIY craze?

A.Young people liked to follow the fashion.

B.“Do-It-Yourself” is a booming business.

C.There were fewer building companies.

D.High cost of professional workers.小题4:What is the speaker telling us ?

A.How DIY comes into being.

B.Changes in building.

C.Changes in housing.

D.Great changes in these thirty years.