电场中有一点P，下列说法中正确的是（） A．若放在P点的电_爱下问搜题

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问题选择题

电场中有一点P，下列说法中正确的是（　　）

A．若放在P点的电荷的电荷量减半，则P点的场强减半

B．若P点没有试探电荷，则P点场强为零

C．P点的场强方向为放在该点的负电荷的受力方向

D．P点的场强大小和方向与放入的试探电荷无关

答案

A、场强反映电场本身的强弱和方向，由电场本身决定，将放在P点的电荷的电荷量减半，P点的场强不变．故A错误．

B、场强是由电场本身决定的，与试探电荷无关，若P点没有试探电荷，P点场强不变，不为零．故B错误．

C、场强方向是放在该点的正电荷的受力方向，与放在该点的负电荷的受力方向相反．故C错误．

D、场强是描述电场本身性质的物理量，与放入电场的试探电荷无关．故D正确．

故选D

单项选择题

信息系统的可行性研究包括

A．管理可行性、运行可行性、维护可行性

B．硬件可行性、软件可行性、数据可行性

C．技术可行性、经济可行性、运行可行性

D．目标可行性、规模可行性、投资可行性

完形填空

Alone in the light at the dining room table, surrounded by a nearly dark house, I sat in tears.
Finally, I 36 in getting both kids to bed. As a new single 37 , I had to be both Mommy and Daddy to my two little children.
With full rights of my children, I 38 to give them a normal and comfortable home life. I 39 a happy face for them.
I rose slowly, trying not to 40 even the least sound which might start them up 41 . I tiptoed(蹑手蹑脚地走) out of their room, 42 the door part way, and went downstairs.
And loneliness(孤独). I 43 as thought I were at the bottom(底部) of a great sea of loneliness. It all 44 together and I was at once lost. I sat there, 45 crying.
Just then, a pair of little 46 went around my middle and a little face looked up at me. I looked down into my five-year-old son’s 47 face.
I was shy to be 48 crying by my son. “I’m sorry. Ethan, I didn’t know you were stillo awake.” I don’t know why, but so many people 49 when they cry and I was no exception. “I didn’t 50 to cry. I’m just a little 51 tonight.”
“It’s okay, Daddy. It’s okay to cry; you’re just 52 .”
I couldn’t express(表达) how happy he made me, this little boy, who was simple, gave me 53 to cry. He seemed to be saying that I didn’t have to always be 54 , and that sometimes it was possible to allow myself to feel weak and let out my 55 .

A．experienced