阅读理解
When you are little, the whole world feels like a big playground.I was living in Conyers, Georgia the
summer it all happened.I was a second grader, but my best friend Stephanie was only in the first grade.
Both of our parents were at work and most of the time they let us go our own way.
It was a hot afternoon and we decided to have an adventure in Stephanie's basement.As I opened the
basement door, before us lay the biggest room, full of amazing things like guns, dolls, and old clothes.I
ran downstairs, and spotted a red steel can.It was paint.I looked beyond it and there lay even more paint
in bright colors like purple, orange, blue and green.
"Stephanie, I just found us a project for the day.Get some paintbrushes.We are fixing to paint."She
screamed with excitement as I told her of my secret plans and immediately we got to work.We gathered
all the brushes we could find and moved all of our materials to my yard.There on the road in front of my
house, we painted big stripes(条纹)of colors across the pavement(人行道). Stripe by stripe, our colors
turned into a beautiful rainbow.It was fantastic!
The sun was starting to sink.I saw a car in the distance and jumped up as I recognized the car.It was
my mother.I couldn't wait to show her my masterpiece.The car pulled slowly into the driveway and from
the look on my mother's face, I could tell that I was in deep trouble.
My mother shut the car door and walked towards me.Her eyes glaring, she shouted, "What in the
world were you thinking?I understood when you made castles out of leaves, and climbed the neighbors'
trees, but this!Come inside right now!"I stood there glaring back at her for a minute, angry because she
had insulted(侮辱)my art.
"Now go clean it up!"Mother and I began cleaning the road.Tears ran down my cheeks as I saw my
beautiful rainbow turn into black cement.
Though years have now passed, I still wonder where my rainbow has gone.I wonder if, maybe when
I get older, I can find my rainbow and never have to brush it away.I guess we all need some sort of
rainbow to brighten our lives from time to time and to keep our hopes and dreams colorful.
。在x轴下方的虚线（虚线与茗轴成45°角）右侧有垂直纸面向外的匀强磁场，磁感应强度为B。有一长为L的轻绳一端固定在第一象限内的O′点，且可绕O′点在竖直平面内转动；另一端拴有一质量为m的小球，小球带电量为+q。OO′与x轴成45°角，其长度也为L。先将小球放在O′点正上方，从绳恰好绷直处由静止释放，小球刚进人有磁场的区域时将绳子断开。
，做匀加速直线运动。设绳子第一次刚拉直还没有开始绷紧时小球的速度大小为v。根据动能定理可得：
…………………………………………①（2分）
………………………③（2分）
……………………………………………………………………⑥（3分）
………………………………………………………⑦（2分）
………………………………………………………………⑧（2分）