问题
单项选择题
X线管阴极是（）
A.电子发射器
B.电子收集器
C.靶面
D.二极管
E.X线管窗口
答案
参考答案：A
解析：阴极在X线管中的作用是发射电子，并使之适当聚焦，所以可称为电子发射器。
搜题请搜索小程序“爱下问搜题”
X线管阴极是（）
A.电子发射器
B.电子收集器
C.靶面
D.二极管
E.X线管窗口
参考答案：A
解析：阴极在X线管中的作用是发射电子，并使之适当聚焦，所以可称为电子发射器。
I was driving around downtown one afternoon in the winter. I 1 a red light and stopped. As I was 2 , I saw a young guy standing on my left. He was 3 in the face and holding a cardboard sign with some 4 on it. When you’re in the heart of downtown, it’s pretty 5 to see homeless people asking for 6 . Generally, I would pass them, but this time when I glanced over the sign, I 7 . I can’t remember what the sign said exactly, but it was something like: “ 8 money / food, have stomach cancer, homeless, anything helps.” I didn’t know why, but for some 9 this particular sign struck me. The 10 had just turned green, and there was a line of lunch rush hour traffic behind me. I went back and forth in my 11 a hundred times in that next 12 about whether I should do something. “Should I help? 13 on? Should I do something?” I didn’t. I did nothing. The traffic moved 14 , and I went with it. About a block（街区）or two away, my heart had sunk simply for this guy. I felt so 15 for him. So, I decided to go back and ask him 16 I could buy him lunch and hear his story. It took me about five minutes to 17 and back on to the same street where I had seen him. It was just five minutes — but he was 18 . “Where did he go so fast?” I wondered. So, there was 19 left to do except drive on. If you get a special nudge（想做的事）from inside you, 20 consider acting on it. Don’t miss out — for yourself and for that other person.
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