以下哪一个可以用来保证计算机能在良好的环境里持续工作（）
A.环境安全
B.实体安全
C.运行安全
D.信息安全
参考答案：C
---This is a photo of _________ when they were young.
---OK, how happy they both looked!
A．my father and mother
B．my mother and father's
C．my mother's and father's
D．my father's and my mother
A．I= ，从上向下
B．I= ，从上向下
C．I= ，从下向上
D．I= ，从下向上
