用伏安法测电阻时,由于电压表、电流表内阻的影响,测量结果总存在系统误差。按下图甲

题型:实验题

问题:

用伏安法测电阻时,由于电压表、电流表内阻的影响,测量结果总存在系统误差。按下图甲所示的电路进行测量,可以消除这种系统误差。

(1)该实验的第一步是:闭合开关S1,将开关S2接2,调节滑动变阻器Rp和r,使电压表读数尽量接近满量程,读出这时电压表和电流表的示数U1,I1;请你接着写出第二步,并说明需要记录的数据____________________________________。

(2)由以上记录数据计算被测电阻Rx的表达式是Rx=___________。

(3)将图乙中给出的仪器按照电路图的要求连接起来,

考点:实验:伏安法测电阻
题型:实验题

采用砂浆灌竖缝,两侧用夹板夹住砌块,超过3cm宽的竖缝采用不低于( )的细石混凝土灌缝,收水后进行嵌缝,即原浆勾缝。

A.C10

B.C35

C.C20

D.C50

题型:实验题
Are you a man or a mouse? When people ask this question they want to know 31   you are a   32  person or a coward(懦夫). But you will never really know the answer to this question  33  you are tested in real life. Some people  34  they are brave but when they come face to face with real  35 , they act like cowards. Others think of themselves as cowards, but when they meet danger, they act like  36 .
Lenny had always thought of himself as a  37  person. He got worried before examinations. He worried about his job and health. All he wanted in life was to be safe and healthy.  38 , on January 15th, 2002, a plane crashed into the Potomac River in Washington. Lenny went to the river to see what was happening. He saw a woman in the  39  water. Lenny did not feel afraid. He kept very  40  and did a very dangerous thing. He jumped into the Potomac, 41  to the woman, and kept her head  42  the water. Seventy-eight people died that day. Thank to Lenny, it was not  43 .
When you are in a very  44  situation and feel afraid, the body automatically produces a chemical in the blood. The chemical is called adrenalin(肾上腺素). 45 adrenalin in the blood system, you will feel stronger and stronger and are  46 to fight or run away. However, when you are absolutely terrified, the body can produce too much adrenalin. When this  47 , the muscles become very hard and you find you  48  move at all. You are then paralyzed(使瘫痪,使麻痹) with fear. This is  49  when we are very frightened, we sometimes say we’re “petrified”, which means “stone”. We are   very frightened 50  we become stonelike.
小题1:
A.howB.neitherC.whetherD.either
小题2:
A.braveB.realC.hardD.certain
小题3:
A.whenB.untilC.afterD.once
小题4:
A.realizeB.findC.thinkD.agree
小题5:
A.lifeB.questionC.mouseD.danger
小题6:
A.soldiersB.miceC.heroesD.cowards
小题7:
A.usefulB.braveC.nervousD.terrible
小题8:
A.SoB.ThereforeC.ThenD.Actually
小题9:
A.freshB.poisonousC.warmD.ice-cold
小题10:
A.nervousB.calmC.frightenedD.excited
小题11:
A.wentB.helpedC.spokeD.swam
小题12:
A.inB.underC.aboveD.from
小题13:
A.an accidentB.a mistakeC.seventy-eightD.seventy-nine
小题14:
A.dangerousB.comfortableC.differentD.favorable
小题15:
A.WithB.WithoutC.ForD.Like
小题16:
A.afraidB.unableC.readyD.anxious
小题17:
A.getsB.disappearsC.happensD.goes
小题18:
A.needn’tB.can’tC.mustn’tD.shouldn’t
小题19:
A.whereB.howC.becauseD.why
小题20:
A.thatB.for C.suchD.so
题型:实验题

果岭

题型:实验题

小儿急性肠套手术治疗最重要的依据是()

A.患儿年龄小

B.排果酱样便

C.呕吐物为胆汁样物

D.发病超过48小时

E.行空气灌肠无效

题型:实验题

《中华人民共和国治安管理处罚法》由中华人民共和国第十届全国人民代表大会常务委员会第十七次会议于2005年8月28日通过,自2006年5月1日起施行。

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