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问题 实验题

由下列所给定的器材中选出适当的实验器材，设计一个测量阻值约为15kΩ的电阻的电路，要求方法简捷，尽可能提高测量的精度：  

电流表A1，量程1mA，内阻rA1约为50Ω  

电流表A2，量程300μA，内阻rA2约为300Ω  

电流表A3，量程100μA，内阻rA约为500Ω  

电压表V1，量程10V，内阻rV1=15kΩ  

电压表V2，量程3V，内阻rV2=10kΩ  

滑动变阻器R，总阻值50Ω，额定电流为1A  

电池组，电动势3V，内阻很小但不能忽略  

开关、导线若干  

(1)测量电路中的电流表应选________，电压表应选________（填代号）；  

(2)在线框中画出测量Rx的电路图；

(3)在所测量数据中选一组数据计算Rx，计算Rx的表达式为________，表达式中各符号表示的意义是________。

答案

(1)A2；V2

(2)如图所示

；U2、I2分别为电压表V2、电流表A2的读数

单项选择题

需设置开展化学测定和仪器分析检验室的是

A．小型药品批发和零售连锁企业
B．大型药品批发和零售连锁企业
C．企业主要负责人
D．药品零售药店
E．执业药师
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单项选择题

Now which are the animals really to be pitied in captivity First, those clever beings whose lively urge for activity can find no outlet behind the bars of the cage. This is most conspicuous, even for the uninitiated, in the case of animals which, when living in a free state, are accustomed to roaming about widely. Owing to this frustrated desire, foxes and wolves housed, in many old-fashioned zoos, in cages which are far too small, are among the most pitiable of all caged animals.
Though pinioned swans generally seem happy, under proper care, by hatching and rearing their young without any trouble, at migration time things become different: they repeatedly swim to the lee side of the pond, in order to have the whole extent of its surface at their disposal, trying to take off. Again and again the grand preparations end in a pathetic flutter of their half wings ; a truly sorry picture !
This, however, rarely awakens the pity of the zoo visitor, least of all when such an originally highly intelligent and mentally alert animal has deteriorated, in confinement, into a crazy idiot, a very caricature of its former self. Sentimental old ladies, the fanatical sponsors of the societies for Prevention of Cruelty to Animals, have no compunction in keeping a grey parrot in a relatively small cage or even chained to a perch. Together with the large corvines, the parrots are probably the only birds which suffer from that state of mind, common to prisoners, namely, boredom.

According to the author in Paragraph 1, what animals suffer most in captivity

A．Climbing animals.

B．Hunting animals.

C．Parroting animals.

D．Singing animals.
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