在电场中A点放一检验电荷+q，所受电场力为F．A点的场强为E ，下_爱下问搜题

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问题选择题

在电场中A点放一检验电荷+q，所受电场力为F．A点的场强为E ，下列正确的是

A．若移走检验电荷，A点的电场强度为零

B．若在A点放电荷量为+2q的检验电荷，则A点的电场强度为2E

C．若在A点放电荷量为-q的检验电荷，则A点的电场强度为－E

D．若在A点放电荷量为-q的检验电荷，检验电荷在A点受到的电场力为-F

答案

答案：D

题目分析：电场中某点场强的天小和方向由电场本身决定，与放入该点的检验电荷无关，与在该点是否放检验电荷无关故选D

点评：本题难度较小，明确是电场强度的定义式，适用于任何电场，切记电场中某点的电场强度完全由电场本身决定，与放不放电荷，放入的电性及电荷量的多少无关

完形填空

Four years ago,an accident took my wife away and I had to take care of our youny child . There was one particular night, when I had an __36__ at work. Therefore, I __37_ cooked an egg and left my sleepy child alone at home.
It was very late when I __38__. With just a brief hug and kiss for my child, I went stright into the room, without having dinner. __39__, when I jumped into my bed , all I heard and felt was broken sounds and __40__ liquid. I opened my blanket, and there _41__ the source of the “problem”—a broken bowl with noodels and a mess on the bed.
I was so _42_ that I rushed into Loe’s room and gave him a good spanking. He __43__ cried but didn’t ask for mercy, except a short explanation.
“Dad, I was _44__, but you were not back yet, so I wanted to cook some noodles.But I remembered that you __45_ me not to touch or use the kitchen without any __46__ around; therefore, I __47__ the shower and used the hot water to cook the noodles.However, I was __48__ that the noodles would turn cold, so I put it under the__49__ to keep it warm __50__ you return. But I forgot to remind you.”
I went towards my son to give him a(n) __51__ hug and asked him to sleep. Then I began to _52__ the mess on the bed. When everthing was done, I passed my son’s room, and saw that he was still __53__ while looking at his mother’s photo.He cried not for the __54__ on his little body. After this _55__, I have tried to give him both the love of dad and mum.
小题1:

D．communication

多项选择题

要将电气设备从运行状态变换到检修状态，就要（）等，这些工作即为倒闸操作。

A.拉开关

B.拉刀闸

C.验电、装设接地线

D.悬挂标示牌、装设遮栏

E.填写操作票

F.工作许可