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问题 选择题

下列关于用高倍显微镜观察叶绿体实验的叙述正确的是[ ]

A．因为藓类叶片大，在高倍镜下容易找到，所以可以直接使用高倍物镜观察

B．在低倍镜下找到叶片细胞，即可换上高倍物镜

C．换上高倍物镜后，必须先用粗焦螺旋调焦，再用细准焦螺旋调至物像最清晰

D．若视野中部分细胞能看得清晰，另一部分细胞看不清楚，可能是由于材料的薄厚不均

答案

答案：D

情景交际

情景对话

根据对话情景和内容，从对话后所给的选项中选出能填入空白处的最佳选项。选项中有两项为多余选项。

A. You are lucky to be in such a big city where everything is wonderful.

B: I don’t think so. ___1___

A: Why? City life seems to be very interesting and comfortable.

B: ___2___ You see citizens are obliged to accept an unnatural way of life. They can hardly enjoy sunshine because of tall buildings around their houses.

A: That’s terrible. ___3___

B: Yes, perhaps. But the cost of living is much higher. ___4___

A: I didn’t think of that. Now I’d rather live in my village all my life. Would you like to go to the country for a change?

B: Great! ___5___  

A. But working in a big city means much more money without hard work like farming.

B. Actually I don’t have interest in city life.

C. I think country life is as interesting as city life.

D. Not really.

E. Sometimes people can’t make ends meet these years.

F. So it is.

G. I’d love to if I’m free.

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问答题 计算题

变形区长度L=90mm，轧辊工作直径D＝600mm，求压下量Δh。
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