why do some stations keep silence?（）

A.Because they are not engaged in the distress traffic

B.they will affect the transmission of the distress traffic

C.The powers of these stations are very weak

D.They are not in charge of search and rescue

加气机应具有充装和计量功能，其中，加气枪加气的流量不应大于（）m³/min（工作状态）。

A、0.3

B、0.5

C、0.35

D、0.25