下列说法正确的是( ) A.自由电荷的运动必定形成电流 B.形成电流必须要有自由

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问题:

下列说法正确的是(  )

A.自由电荷的运动必定形成电流

B.形成电流必须要有自由电荷

C.形成电流必须要有电压

D.有电压必定形成电流

考点:电流路端电压
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如图所示,质量为m,边长为L的正方形线框,在有界匀强磁场上方h高处由静止自由下落,线框的总电阻为R,磁感应强度为B的匀强磁场宽度为2L.线框下落过程中,ab边始终与磁场边界平行且处于水平方向.已知ab边刚穿出磁场时线框恰好做匀速运动.求:

(1)cd边刚进入磁场时线框的速度;

(2)线框穿过磁场的过程中,产生的焦耳热.

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Every human being is fallible; we make mistakes. In America when a mistake has been made, it is considered fitting for the person (1) to acknowledge his or her error and to apologize to anyone who has been inconvenienced. Even (2) are expected to admit their mistakes and apologize for them. Trying to (3) a mistake and denying your guilt are considered to be indicative of serious (4) .
If you make a mistake that (5) a group of people, a public apology is considered the best method for (6) . If the mistake was a serious one, or if some people were inconvenienced more than others, then the (7) should follow the public apology with private ones to (8) .
It is especially important for executives and company heads to be able to admit their mistakes. Sometimes leaders are afraid that if they (9) , they will lose the respect of their employees. Actually (10) — if you are honest with your employees and yourself, (11) , and show that you are willing to accept blame when you make a mistake, then your employees will be (12) you. They will also be more likely to admit their own mistakes.
If you (13) one person, it is usually best to apologize to that person alone, unless your mistake (14) by a large group of people. For example, if Leonard (15) to Mr. Todd during a committee meeting, it would be (16) for Leonard to apologize to Mr. Todd at the next committee meeting. If the (17) created by the initial mistake is public, then the apology should be public. However, if Leonard raised his voice to Mr. Todd when only the two of them (18) , he may apologize privately. Notice as well (19) the apologies are. As soon as you realize you have made a mistake, you should (20) .

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轿车上多设有回油管路,这种汽车汽油泵供油量较化油器的出油量大得多,多余燃油经回油管流回油管。

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用摇表摇测绝缘子的绝缘电阻时,应选用()。

A、2300V的摇表

B、2000V的摇表

C、1000V的摇表

D、5000V的摇表

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下列属于所有权凭证的金融工具是( )。

A.公司债券
B.股票
C.政府债券
D.可转让大额定期存单

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