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问题 单项选择题

临床用于确诊宫颈癌的辅助检查是（）

A.宫颈刮片

B.宫颈和宫颈管活检

C. * * 脱落细胞检查

D.宫腔镜

E. * * B超

答案

参考答案：B

解析：宫颈和宫颈管活组织检查是确定宫颈癌前病变和宫颈癌的最可靠方法。

问答题

如图所示，与纸面垂直的竖直面MN的左侧空间中存在竖直向上场强大小为E的匀强电场（上、下及左侧无界）．一个质量为m、电量为q=mg/E的可视为质点的带正电小球，在t=0时刻以大小为V0的水平初速度向右通过电场中的一点P，当t=t1时刻在电场所在空间中加上一如图所示随时间周期性变化的磁场，使得小球能竖直向下通过D点，D为电场中小球初速度方向上的一点，PD间距为L，D到竖直面MN的距离DQ为L/π．设磁感应强度垂直纸面向里为正．

（1）如果磁感应强度B0为已知量，试推出满足条件时t1的表达式（用题中所给物理量的符号表示）

（2）若小球能始终在电场所在空间做周期性运动．则当小球运动的周期最大时，求出磁感应强度B0及运动的最大周期T的大小．

（3）当小球运动的周期最大时，在图中画出小球运动一个周期的轨迹．
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单项选择题

There are many kinds of friends. Some are always (1) you, but don’t understand you. Some say only a few words to you, but understand you. Many people will step in your life, but only (2) friends leave footprints.
I shall always recall the autumn and the girl with the (3) . She will always bring back the friendship between us. I know she will always be my best friend.
It was the golden season. I could see the yellow leaves (4) with the cool (5) . In such a season, I liked walking alone on the roads covered with leaves, (6) to the sound of them.
Autumn is a (7) season and life is uninteresting. The free days always get me (8) . But one day, the sound of a violin (9) into my ears like a stream flowing in the mountains. I was so surprised that I jumped to see what it was. A young girl, standing in the wind, was (10) in playing her violin.
I had (11) seen her before. The music was so nice that I listened quietly. Lost in the music, I didn’t know that I had been (12) there for so long but my existence did not seem to disturb her.
Leaves were still falling. Every day she played the violin at the comer of the building (13) I went downstairs to watch her performance. I was the only listener. The autumn seemed no longer lonely and life became (14) . (15) we didn’t know each other, I thought we were already good friends. I believe she also loved me.
Autumn was nearly over. One day, when I was listening carefully, the sound suddenly (16) . To my astonishment, the girl came over to me.
"You must like music from the violin." she said.
"Yes. And you play very well. Why did you stop’." I asked.
Suddenly, a (17) expression appeared on her face and I could feel something unusual.
"I came here to see my grandmother, but now I must leave. I once played very badly. It was your listening every day that (18) me. " she said.
"In fact, it was your playing (19) gave me a meaningful autumn," I answered, " Let’s be friends. "
The girl smiled, and so did I. I never heard her play again in my life. I no longer went downstairs to listen to her. Only thick leaves were left behind. But I will always remember the fine figure of the girl. She is like a (20) —so short, so bright, like a shooting star giving off so much light that makes the autumn beautiful.

Ⅱ. 完形填空/Close

A．song

B．dream

C．fire

D．sister
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