金属壳雷管标注时，字码痕迹深度不应小于（）。
A、6μm
B、0.5mm
C、1mm
D、5mm
参考答案：A
An analyst does research about security market indices. Which of the following indices is most likely subject to survivorship bias（）
A. Fixed-income indices.
B. Hedge fund index.
C. Real estate investment trust index.
骨骺损伤以（）型损伤诊断较困难。
A.Ⅰ型
B.Ⅱ型
C.Ⅴ型
D.Ⅳ型
E.Ⅲ型
