Both sorts, moreover, can be switched between passive, listening mode, and active, destructive mode.

此外，这两种类型都可以在被动、聆听模式和主动、破坏性模式之间切换。

Oh, the SOS signal on the u-boat was designed to go into a passive mode, which means we'd have to be right on top of it in order to detect it.

潜艇上的求救信号被设计成被动模式，也就是说我们得站在潜艇上才能检测到。