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问题 填空题

某电流表mA的量程为I0=50mA，内阻为r0=50Ω，其表盘刻度线已模糊不清，要重新通过测量来刻画出从零到满刻度的刻度

值，有下列器材：

A．待测电流表mA

B.6V直流电源E

C．“0～10Ω，1A”滑动变阻器R1

D．“0～100Ω，50mA”滑动变阻器R2

E．“0.6A，0.5”标准电流表A1

F．“3A，0.01”标准电流表A2

G.5Ω定值电阻R3

H.20Ω定值电阻R4

I．开关及导线若干

（1）应选用的器材有______（只需填写所选器材序号）．

（2）在虚线框内画出实验电路图．

（3）待测电流表的电流刻度值的表达式I=______，式中各物理量所表示的意义分别为______．

答案

（1）先选出必选的ABI，再据电路需求选择相应器材：因电压变化范围大故滑动变阻器用分压式接法，用小阻值的C，

待较准的电流表的最大电压为I0r0=2.5V，则当作电压表的电流表与电阻选择E，G即可．故所选器材为：ABCEGI．

（2）电路图如图所示

（3）由电路图可知，流过待较准电流表的电流为：I=

I1(RA1+R3)
r0
，I1为标准电流表A1的读数，RA1为标准电流表A1的内电阻，r0为待测交电流表的电阻，R3为定值电阻阻值

故答案为：（1）ABCEG

（2）电路如图

（3）

I1(RA1+R3)
r0
   I1为标准电流表A1的读数，RA1为标准电流表A1的内电阻，r0为待测交电流表的电阻，R3为定值电阻阻值

填空题

危害因素存在的多少或导致后果程度的大小叫做（）。
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单项选择题

The International Whaling Commission’s (IWC) decision to retain its ban on whaling does not mean that the killings will stop. Quite the (1) .

Save the Whale. It’s a phrase which became annoying with (2) , an unfavorable shorthand for liberal consciences. How appalling, then, that in the year 2010, it should be pressed (3) service again, to fight the whaling nations: Norway and Iceland, who exempted themselves from the 1986 prohibition (4) by the IWC, and Japan, which hunts whales under cover of " (5) research".

I am completely (6) by this week’s events in Morocco, where talks broke down. In my heart, I agree with those who have (7) the news that this year’s negotiations of the IWC have broken up, and (8) the prohibition would not be lifted (as the US proposed in a desperate (9) to break the deadlock). Yet reason (10) something else. If we do not (11) some kind of new control, the (12) will be able to go on with their slaughter (13) . Membership of the IWC is (14) , and the ban was only ever intended to be (15) . Japan, which has been buying the votes of nations with no interest in whaling (only in the 16 Japan offers in turn), will continue to press its case, having invested millions of dollars in its (17) . Geoffrey Palmer, New Zealand’s Commissioner at the IWC, has proposed a year-long (18) period. In the meantime, more whales will die.

We stand at a crossroad for whales. We see the (19) existence of these animals as an indicator of ecological threat. As symbols of an endangered world, they evoke, and provoke, a feeling that they have the same qualities as human on a scale equal to their size and supposed (20) . To some this is so much sentimental words in the New Age.

3（）

A.to

B.for

C.into

D.of
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