一根螺位错在(111)面上运动，若在运动过程中遇到障碍物而发生交滑移，则交滑移系统为（ ）
A、
B、（111）
C、
D、

单项选择题A． B． C． D．

单项选择题According to BOM and MRP, to ensure normal production, does material O need to be ordered? If an order is needed, when should it be placed? What is the order quantity? Figure 1. Bill of materials Table 1. Material requirement Planning of X