选择机器MU应之一的主要项目是()
A、长期医嘱
B、当日医嘱
C、照射野大小
D、百分深度量
E、校后的PDD
参考答案：B
The owner of the cinema needed to make a lot of improvements and employ more people to keep it
running, _ meant spending tens of thousands of pounds.[ ]
A. who
B. that
C. as
D. which
在匹配病例对照研究时，为了节约样本，提高效率，常用1：A4配比，但A4的取值一般（）
A.<2
B.<3
C.<4
D.<5
E.<6
