题干

小明利用热敏电阻设计了一个“过热自动报警电路”,如图甲.将热敏电阻R安装在需要探测温度高低的地方,当环境温度正常时,指示灯亮;当环境温度超过某一值时,警铃响.图甲中继电器的供电电压U1=6V,继电器线圈的电阻R0为30Ω,当线圈中的电流大于等于100mA时,警铃响.图乙是热敏电阻的阻值随温度变化的图象.下列说法正确的是(   )

A:图中接线柱A与D连接,B与C连接

B:图甲电磁铁下端P的磁极应为S极

C:当环境温度升高,电磁铁的磁性减弱

D:环境温度达到80℃时,警铃响

上一题 下一题 0.0难度 选择题 更新时间:2018-10-02 02:05:26

答案(点此获取答案解析)

B,D

同类题5

根据短文内容,从短文后的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

Evaluating (评价)Sources of health Information

Makinggood choices about your own health requires reasonable evaluation. A key firststep in bettering your evaluation ability is to look carefully at your sourcesof healthy information. Reasonable evaluation includes knowing where and how tofins relevant information, how to separate fact from opinions, how to recognizepoor reasoning, and how to analyze information and the reliability of sources.____ 

Goto the original source. Media reports often simplify the results of medicalresearch. Find out for yourself what a study really reported, and determinewhether it was based on good science. Think about the type of study.____

Watchfor misleading language. Some studies will find that a behavior “contributesto” or is “associated with” an outcome; this does not mean that a certaincourse must lead to a certain result.____ Carefully read or listen toinformation in order to fully understand it.

Useyour common sense. If a report seems too good to be true, probably it is. Beespecially careful of information contained in advertisements.____ Evaluate “scientific” statements carefully,and be aware of quackery(江湖骗术).____ Friends and family members can be a greatsource of ideas and inspiration, but each of us needs to find a healthylifestyle that works for us.

Developingthe ability to evaluate reasonably and independently about the health problemswill serve you well throughout your life.

A.The goal of an ad is to sell yousomething.

B.Make choices that are right for you.

C.And examine the findings of theoriginal research.

D.Be sure to work through the criticalquestions.

E.Distinguish between research reportsand public health advice.

F.The following suggestions can help yousort through the health information you receive from common sources.

G.Be aware that information may also beincorrectly explained by an author's point of view.