如图所示，三根彼此绝缘的无限长直导线acef构成一个等边三角形，O为

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• 1下列说法中正确的是（  ）

  A：由B=F/IL可知，磁感应强度B与一小段通电直导线受到的磁场力成正比

  B：一小段通电导线所受磁场力的方向就是磁场方向

  C：一小段通电导线在某处不受磁场力，该处磁感应强度一定为零

  D：磁感应强度为零的地方，一小段通电导线在该处不受磁场力

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• 2下列单位符号中不能表示磁感应强度单位的是（  ）
  下列单位符号中不能表示磁感应强度单位的是（  ）

  A：N/C

  B：N/Am

  C：

  D：

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• 3全自动洗衣机中，排水电磁阀是由程序控制器控制其动作的。当洗衣机
  全自动洗衣机中，排水电磁阀是由程序控制器控制其动作的。当洗衣机进行排水和脱水工序时，电磁铁的线圈通电，使电磁铁的铁芯2动作，牵引排水阔的活塞打开，排除污水。牵引电磁铁的结构如图所示。当程序控制器的控制电流通过线圈时，线圈和铁芯1产生一个强的磁场，使铁芯2磁化，由于磁体相互作用，将铁芯2吸入线圈，此时铁芯2将拉动阀门使阀门打开排水。同样，控制器不输出控制电流时，电磁铁将失去磁性，弹簧（图中未画）将铁芯 2拉回原位，从而关闭阀门（     ）

  A：某时刻输入控制电流时，a为正，b为负，则铁芯2中A端为N极、B端为S极

  B：某时刻输入控制电流时，a为正，b为负，则铁芯2中A端为S极、B端为N极

  C：若a、b处输入的是正、负交变电流，铁芯2不能被吸入线圈

  D：若a、b处输入的是正、负交变电流，铁芯2能被吸入线圈

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• 4I don’t mind her criticizing me, but ______ is how she does
  I don’t mind her criticizing me, but ______ is how she does it that I object to.

  A：it

  B：that

  C：this

  D：which

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• 5Both of them refused to say sorry and neither was willing to
  Both of them refused to say sorry and neither was willing to talk to       .

  A：others

  B：the other

  C：other

  D：one another

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• 6-Would you get me a bar of chocolate from the kitchen,dear?-
  -Would you get me a bar of chocolate from the kitchen,dear?-          one?                                         

  A：Other

  B：Every

  C：Another

  D：More

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• 7Nobody but me ______ that either you or Tom ______to take pa
  Nobody but me ______ that either you or Tom ______to take part in this activity.

  A：knows / is

  B：know / are

  C：know / is

  D：knows / are

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• 8I don’t think ___ possible to travel around the world witho
  I don’t think ___ possible to travel around the world without any modern equipment．

  A：this

  B：that

  C：its

  D：it

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• 9---Did a letter come for me?---Yes, ____ came for you when I
  ---Did a letter come for me?---Yes, ____ came for you when I was on the point of going out this morning.

  A：that

  B：it

  C：one

  D：this

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• 10You should make ______ a rule to leave things______ you can
  You should make ______ a rule to leave things______ you can find them easily.

  A：it; where

  B：it; then

  C：that; there

  D：this; when

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