—       will your parents return?

—They will return in a week.

A．How often

B．How long

C．How much time

D．How soon

《建筑消防安全检测评价技术规程》规定，水雾灭火系统的工作压力，当用于灭火时不应小于0.35MPa用于防护冷却时不应小于（）MPa

A.0.5

B.0.3

C.0.2

D.0.4