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问题 选择题

用显微镜观察洋葱表皮装片，先后用15×目镜和10×物镜与10×目镜和45×物镜观察洋葱表皮同一部位，结果两次看到的（   ）

A．视野都一样亮

B．物像都是倒像

C．细胞数目一样多

D．细胞大小都相同

答案

答案：B

题目分析：显微镜的放大倍数指的是物镜和目镜放大倍数的乘积．使用目镜15×和物镜10×，放大倍数为15×10═150倍，使用目镜10×和物镜45×，放大倍数为10×45═450倍，观察洋葱同一部，由于第二种情况比第一种情况显微镜的放大倍数增大，在视野中看到的细胞数目减少，细胞的体积增大，视野变暗，但所观察到的物像都是倒像。

点评：此题为基础题，解此题的关键是理解掌握显微镜的主要结构和功能以及使用方法。

选择题

下列各式成立的是（　　）

A．a-b+c=a-（b+c）

B．a+b-c=a-（b-c）

C．a-b-c=a-（b+c）

D．a-b+c-d=（a+c）-（b-d）
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完形填空
It’s a sad and familiar sentence from a beggar that we often hear. Usually, when asked “Can you spare some   36  ?” I’ve been struck with a feeling of   37  if I passed by without giving a coin or two.
My conscience was hurt again when I was making a   38  in Venice in 2006. I was sitting in a quiet café. Outside the café on the street was an old woman on her knees,    39 . Steady streams of   40  were walking past her. A young backpacker stood away from the crowd drinking something, but I noticed he was also    41   the woman.
She knelt motionlessly, her head almost touching the ground, a worn blanket providing little    protection   42   the cold. The sight was especially   43  when compared with the signs of the   44  city around her.
A tourist group hurried along the street,   45  at the woman and walked on. Another group of tourists arrived,   46  again, walked past her. The backpacker watched. Then, as I prepared to leave, I stopped at the sight of the backpacker   47  and placing some money in the woman’s cup. He did this rather   48 , just before the arrival of another tourist group. I watched   49  the leader of the group stopped and put some money in the cup. With the young man   50  the way, other tourists followed.
The young backpacker   51  this process in front of the next tour party going past. Once again, the subtle peer(同伴) pressure   52  on the tourists, who all added coins to the cup. His work   53 , the young man walked over to the old beggar woman and said, “I hope that helps a bit.”
I placed some money in the woman’s cup and  54  my tour, light-hearted after witnessing such a   55  act of caring.
小题1:
A．timeB．effortC．change D．reward
小题2:
A．satisfactionB．guiltC．angerD．pleasure
小题3:
A．lecture B．reportC．studyD．tour
小题4:
A．cryingB．beggingC．singingD．dancing
小题5:
A．passengersB．customersC．touristsD．foreigners
小题6:
A．ignoringB．servingC．observingD．following
小题7:
A．againstB．forC．withD．in
小题8:
A．frighteningB．touchingC．fascinatingD．interesting
小题9:
A．peacefulB．noisyC．wealthyD．primitive
小题10:
A．glancedB．laughedC．shoutedD．stared
小题11:
A．unlessB．soC．butD．or
小题12:
A．looking aroundB．stepping forwardC．getting aboutD．breaking in
小题13:
A．secretlyB．carelesslyC．deliberatelyD．eagerly
小题14:
A．sinceB．beforeC．afterD．as
小题15:
A．showingB．showedC．pointingD．pointed
小题16:
A．stoppedB．valuedC．madeD．repeated
小题17:
A．movedB．repliedC．workedD．carried
小题18:
A．doneB．was doneC．has been doneD．had been done
小题19:
A．cancelledB．continuedC．startedD．delayed
小题20:
A．funnyB．smartC．simpleD．modest
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