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问题 计算题

如图所示电路中，电阻R1=R2=3Ω，R3=6Ω，S扳至1时，电流表的示数为1.0A， S扳至2时，电流表示数为1.5A，求：

小题1:电源的电动势E和内阻r（电流表内阻不计）；

小题2: S扳至2时，电源的输出功率。

答案

小题1:E=6.0V，r=1.0Ω

小题2: W

阅读理解

阅读理解。

     Alice is an American girl .She is thirteen. She is now in Beijing with her parents .She doesn't know

 much Chinese. She can't speak Chinese well .Sometimes her friends do not understand her.

    It's Sunday morning .She's going to the zoo to see the pandas .She is waiting at the bus station .At the

 bus station she asks a boy how to go to the zoo .But the boy can't understand    her .Then she takes out

  (拿出) a pen and some paper .She draws a panda on it and shows the picture to the boy .The boy smiles

  and shows the way to the zoo right now.

1. Alice is in Beijing with her _____.

    A. brother    

    B. sister      

    C. uncle    

    D. father and mother

2. Alice can speak _____Chinese

    A much      

    B. little    

    C .few      

    D. many

3. Alice goes to the zoo_____.

    A. on her bike    

    B .on a bus      

    C .in a car    

    D. on a train

4. Alice is going to the zoo to see_____.

    A. her friends    

    B. the tigers    

    C .the monkeys  

    D. the pandas

5.The boy_____.

    A. shows her the way      

    B. doesn't know the way  

    C .goes to the zoo with her  

    D. gives a map to her
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单项选择题

某热水供暖系统，在蒸汽锅炉房内设壳管式汽水换热器和凝结水汽水换热器，加热网路循环水。总热负荷为520×104kJ/h，饱和蒸汽压力为7×105Pa，设凝结水流出凝结水换热器的水温t＝80℃，取换热器效率为965，则蒸汽的流量为（）kg/h。

A．2231

B．2568

C．2903

D．3000
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