问题 多选题

如图所示,边长为L、总电阻为R的正方形导线框abcd放置在光滑水平桌面上,其bc边紧靠磁感应强度为B、宽度为2L、方向竖直向下的有界匀强磁场的边缘.现使线框以初速度v0匀加速通过磁场,下列图线中能定性反映线框从进入到完全离开磁场区域的过程中,线框中感应电流变化的是(  )

A.

B.

C.

D.

答案

AD

阅读理解

阅读理解。

     When I was twelve years old, my family were the first black people to move into an all white part of

Grand Rapids, Michigan. Many of our new neighbors weren't very welcoming. Some of them said angrily

that we should return to where we came from. The children sometimes threw stones at me or drove me

home from school.

     Most of my teachers simply took no notice of me, but not Dorothy Bean, my history teacher. Miss Bean

was angry at how badly I was being treated, but she didn't say this to me. Miss Bean showed her respect

for me by teaching me just like anyone else. Instead of being unnoticed, I was given a chance to show that

I was clever. Miss Bean was the first teacher who ever made me think for myself. She always wanted to

know what I thought about difficult questions. Was Thomas Jefferson right to buy Louisiana from France?

Why? She expected me to have my own idea. Miss Bean was teaching me that thinking for oneself was the

real key to education.

     One day, when I was not paying attention in class, Miss Bean suddenly threw an eraser at me. The eraser

hit me right on the hand and sent my pencil flying. The whole class were very surprised at first, then started

laughing. This event became famous in the school and, because it happened to me, the students wanted to

get to know me. So that's the story of how Dorothy Bean made me her target (靶子), and how I became

just another kid in school.

1. Before the writer's family moved to the new place, _________.

A. some other black people were there

B. there were no black people there

C. the other black people had gone

D. the people there had known them

2. Many people treated the writer badly because he was _________.

A. a new comer

B. not clever

C. a black

D. poor

3. Miss Bean was a teacher who was _________.

A. active and warm-hearted

B. helpful but boring

C. friendly and helpful

D. warm-hearted but careless

4. The underlined words "real key" in the last sentence of Paragraph 2 means _________.

A. important way

B. correct answer

C. free road

D. open door

5. The event that happened between the writer and Miss Bean _________.

A. broke their relationship (关系)

B. made the writer feel worse

C. made the writer a successful man

D. made the writer famous in school

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