问题
单项选择题
当医用加速器的X射线能量高于（）时应在屏蔽设计中考虑中子防护？
A.4MV
B.6MV
C.8MV
D.10MV
E.16MV
答案
参考答案：D
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当医用加速器的X射线能量高于（）时应在屏蔽设计中考虑中子防护？
A.4MV
B.6MV
C.8MV
D.10MV
E.16MV
参考答案：D
| 选词填空。 | |
I __________ to a park with my parents. We __________ many pictures. On the 3rd, I went __________. On the 4th, I __________ elephants in the zoo. On the 5th, I __________ my homework. On the 6th, I _________ presents for my friends. We went back to Beijing by __________ on the 7th. We __________ a good time. |