问题
单项选择题
电子线照射乳腺胸壁野时不正确的是（）
A.机架角为O°
B.装限光筒
C.患者仰卧位
D.升床
E.转小机头
答案
参考答案：A
解析：为保证有较好的剂量分布，通常射线入射方向与胸壁垂直，机架角约为15°～20°。
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电子线照射乳腺胸壁野时不正确的是（）
A.机架角为O°
B.装限光筒
C.患者仰卧位
D.升床
E.转小机头
参考答案：A
解析：为保证有较好的剂量分布，通常射线入射方向与胸壁垂直，机架角约为15°～20°。
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| Life is not easy, so I'd like to say "When anything happens, believe in yourself. " When I was a young boy, I was __1__ shy to talk to anyone. My classmates often __2__ me. I was sad but could do nothing. Later, __3__ happened, and it changed my life. It was an English speech contest. My mother asked me to __4__ it. What a terrible idea! It meant I had to speak __5__ all the teachers and students of my school! "Come on, boy. Believe in yourself. You are sure to __6__." Then mother and I talked about many different topics. At last I __7__ the topic "Believe in yourself ". I tried my best to remember all the speech and  practiced it over 100 __8__. With my mother's great love, I did __9__ in the contest. I could hardly believe my __10__ when the news came that I had won the first place. I heard the cheers (赞美)__11__ the teachers and students. Those classmates __12__ once looked down on (瞧不起) me, now all said "Congratulations!" __13__ me. My motherhugged me and cried excitedly. __14__ then, everything has changed for me. When I do anything, I try to tell __15__ to be sure and I will find myself. This is true not only for a person but also for a country. | ||||
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