Uh, the security camera microphone is unidirectional.

监控摄象头上的麦克风是单向的。

They probably had unidirectional air flow, just like modern birds do, making them very efficient at breathing, even while flying.

它们可能有单向气流，就像现代鸟类一样，这使它们即使在飞行时也能非常有效地呼吸。

This unidirectional current flow could be controlled by varying the voltage to the cathode, which makes it release more or less electrons.

这种单向电流可以通过改变阴极的电压来控制，这使得它释放更多或更少的电子。