用来观察细小的物体用_________镜。用焦距_________ 的作为物镜，_爱下问搜题

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问题填空题

用来观察细小的物体用_________镜。用焦距_________ 的作为物镜，用焦距________ 的作为目镜。（选填“长”或“短”）

答案

显微镜；短；长

多项选择题

龋病的危害性有（）

A.牙冠缺损终致牙丧失

B.牙髓病和根尖周病

C.颌面部间隙感染和颌骨炎症

D.影响消化功能

E.病灶牙，引起远隔脏器的感染

完形填空

In the doorway of my home, I looked closely at my 23-year-old son, Daniel. In a few hours he would be flying to France to   36 a different life. It was a transitional（过渡的）time in Daniel's life. I wanted to    37  him some words of significance. But nothing came from my lips, and this was not the    38 time I had let such moments pass.
When Daniel was five, I took him to the bus stop on his first day of kindergarten. He asked, “What is it going to be like, Dad? Can I do it?” Then he walked   39  the steps of the bus and disappeared inside. The bus drove away and I said nothing. A decade later, a similar   40 played itself out. I drove him to college. As I started to leave, I tried to think of something to say to give him    41 and confidence as he started this new stage of life. Again, words 42 me.
Now, as I stood before him, I thought of those 43  opportunities. How many times have I let such moments   44 ? I don't find a quiet moment to tell him what they have 45 to me. Or what he might   46  to face in the years ahead. Maybe I thought it was not necessary to say anything.
What does it matter in the course of a lifetime if a father never tells a son what he really thinks of him?    47  as I stood before Daniel, I knew that it did matter. My father and I loved each other. Yet, I always   48  never hearing him put his   49   into words. Now I could feel my palms sweat and my throat tighten. Why is it so   50 to tell a son something from the heart?
My mouth turned dry, and I knew I would be able to get out only a few words clearly. “Daniel,” I said, “If I could have picked, I would have picked you.” That's all I could say. He hugged me. For a moment, the world    51 , and there were just Daniel and me. He was saying something, but tears misted my eyes, and I couldn't understand what he was saying. All I was    52 of was the stubble（短须）on his chin as his face pressed   53  mine. What I had said to Daniel was   54 . It was nothing. And yet, it was 55 .

B．instruction

B．discouraged

B．embarrassing

A．disappeared