确定信息安全保护等级的步骤是（）、确定两个指标等级、确定业务子系统等级。
参考答案：赋值
He asked me just to sit down and drink some water ____ I could say anything about my travel plan.
A．while
B．when
C．if
D．before
塑性材料的破坏是以发生断裂为标志的。
