问题 选择题
如图所示,在x轴上方存在着垂直于纸面向里、磁感应强度为B的匀强磁场,一个不计重力的带电粒子从坐标原点O处以速度v进入磁场,粒子进人磁场时的速度方向垂直于磁场且与x轴正方向成120°角,若粒子穿过y轴正半轴后在磁场中到x轴的最大距离为a,则该粒子的比荷和所带电荷的正负是(  )

A.,正电荷

B.,正电荷

C.,负电荷

D.,负电荷

答案

答案:C

阅读理解

We lived in a very quiet neighborhood. One evening I heard a loud crash in the street. Earlier that evening my wife had asked me to go to the store to get some soft drinks. It seemed like this would be a good time to let my teenage daughter Holly practice her driving, so I sent her to the store in my truck.

At dinner my son talked about how much he liked my truck. I enjoyed having it, but I said: "Guy, my heart is not set on that truck. I like it but it is just metal and won’t last forever. Never set your heart on anything that won’t last."

After hearing the loud noise, the whole family ran outside. My son shouted: "Dad! Dad, Holly crashed your truck."

My heart sank and my mind was flooded with conflicting thoughts. Was anyone hurt? Who else was involved? As I ran to the door, I heard a voice in my heart say: "Here is a chance to show Holly what you really love. She’ll never forget it."

The accident had occurred in my own driveway. Holly had crashed my truck into our other vehicle, the family van (搬运车). In her inexperience, she had confused the brakes and the gas pedal. Holly was unhurt physically, but when I reached her, she was crying and saying: "Oh, Dad, I’m sorry. I know how much you love this truck." I held her in my arms as she cried.

Later that week a friend stopped by and asked what had happened to my truck. I told her the whole story. Her eyes moistened (湿润) and she said: "That happened to me when I was a girl. I borrowed my dad’s car and ran into a log that had fallen across the road. I ruined the car. When I got home my Dad knocked me to the ground and began to kick me."

Over 40 years later, she still felt the pain of that night.

I remember how sad Holly was and how I comforted her. One day, when Holly thinks back on her life, I want her to know what really matters in my life.

小题1:How did the crash happen?

A.The van was parked in the wrong place that evening.

B.Holly stepped on the gas pedal instead of the brakes.

C.The brakes of the truck didn’t work properly.

D.Holly was too careless and young to drive a truck.小题2:Why didn’t the writer punish Holly?

A.He was so rich that he didn’t care about losing one truck.

B.He thought there was no point punishing her after the accident.

C.He believed the truck was made of metal and of poor quality.

D.He wanted Holly to know he loved her more than any possessions.小题3:What does the underlined sentence mean?

A.She still suffered physical pain.

B.She felt guilty of damaging the car.

C.It left a deep wound on her soul.

D.She was not forgiven by her Dad.小题4:Which of the following would be the best title for the passage?

A.What really matters?

B.Better to forgive and forget

C.Who is to blame?

D.Accidents will happen

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