一级消防员化学防护服耐寒性：在-25℃±1℃温度下冷冻5min后，无裂纹。
参考答案：对
A firewall is a (72) system designed to (73) an organization’s network aga-inst threats.
A．operating
B．programming
C．security
D．service
直流牵引电动机转子氩弧焊的主要参数有哪些？
