问题 单项选择题

一台设备由三个部件组成,各部件的寿命分布均服从指数分布,且各部件的失效率为每106h分别失效25次,30次,15次,若其中一个失效,设备也失效,则该设备工作1000h其可靠度为()。

A.0.63

B.0.73

C.0.83

D.0.93

答案

参考答案:D

解析:

因为一个部件失效设备就失效,说明各部件之间的功能逻辑关系是串联模型,当各部件寿命服从指数分布,次/106h,所以其工作至1000h的可靠度。

单项选择题

2009年5月份,全国规模以上工业企业(年主营业务收入500万元以上的企业)增加值同比增长8.9%,比上年同期回落7.1个百分点,比上月加快1.6个百分点。
一、从主要行业看,纺织业增长8.3%,化学原料及化学制品制造业增长11.1%,非金属矿物制品业增长14.7%,通用设备制造业增长9.3%,交通运输设备制造业增长12.8%,电气机械及器材制造业增长11.2%,通信设备、计算机及其他电子设备制造业增长4.3%,电力热力的生产和供应业增长1.0%,黑色金属冶炼及压延加工业增长2.3%。
二、从主要产品看,原煤2.5亿吨,同比增长9.6%;原油1603.2万吨,下降1.1%:发电量2838.9亿千瓦时,同比下降2.7%;生铁、粗钢和钢材产量分别为4542.6万吨、4646万吨和5729.1万吨,分别增长6.0%、0.6%和7.4%;水泥1.5亿吨,增长13.5%;汽车114.8万辆,增长29.0%,其中轿车60.8万辆,增长35.0%。
三、工业企业产品销售率为97.34%,同比下降0.49个百分点。工业企业共实现出口交货值5813.6亿元,同比下降15.0%。
1-5月份,全国规模以上丁业企业增加值同比增长6.3%。

2009年5月,以下行业增长率排序正确的是( )。

A.纺织业>通信设备、计算机及其他电子设备制造业>电力热力的生产和供应业
B.电气机械及器材制造业>交通运输设备制造业>化学原料及化学制品制造业
C.通用设备制造业<电力热力的生产和供应业<非金属矿物制品业
D.黑色金属冶炼及压延加工业<纺织业<电力热力的生产和供应业

阅读理解

     Researchers from the University of Newcastle are leading a worldfirst study which builds on earlier

unpublished research that children are most likely to be guided by their father's eating and exercise habits.

     The new study "Healthy Dads, Healthy Kids", led by Associate Professor Philip Morgan from the

designed to help fathers promote and demonstrate to their children positive behaviours related to physical

activity and healthy eating.

     "The earlier findings showed that children are more likely to follow the example set by their father than

their mother when it comes to eating and exercise, " said Morgan.

     Morgan saw striking results in a previous trial involving 165 overweight children.He found children

who lost the most weight had fathers who were engaged in the new eating and exercise plan.

     "We might think mothers are the main influence on children's diet and health, but the reality may be

different, " said Morgan. "The roles of fathers are changing.More families have two parents working and

more fathers are involved with food preparation and food shopping than in the past."

     "Fathers influence the food and physical activity habits in the home through their behaviours, attitudes

and approach to food and eating, and act as a role model to their children, " said Morgan.

     Researchers are inviting fathers who would like to reduce their weight to join the "Healthy Dads,

Healthy Kids" program.Participation involves attending eight sessions (讲习班) at the University of

Newcastle over six months where the men will receive information, have weightrelated measurements

recorded and complete questionnaires.

     Cooking healthy food with the kids and creating a backyard fitness circuit (循环训练场) are among

the assignments (课外作业) for fathers taking part in the study.

1. What do we learn about the  "Healthy Dads, Healthy Kids" program?

A. It aims to build close family relationships.

B. It involves fathers who want to lose weight.

C. It will last more than eight months.

D. It offers free online courses for parents.

2. Morgan finds a link between children's weight loss and________.

A. their parents' efforts  

B. regular sports training

C. balanced diets  

D. their father's influence

3. According to the earlier research, children seem to ________.

A. copy their father's diets and exercise habits

B. develop healthy eating habits by themselves

C. grow taller if their parents often do exercise

D. help their parents to form exercise habits

4. Which of the following facts causes the change of fathers' roles?

A. That kids have more time to spend with family.

B. That more kids need their father's help in learning.

C. That there are more working mothers than before.

D. That fathers become much busier than before.