Most commercial drones are constructed of plastic and are difficult to spot electronically because they're small, fly low to the ground and don't carry a transponder to signal their positions.
而大多数商用无人机的材质都是塑料,加上电子设备很难识别——无人机体型很小,贴近地面飞行,加之没有携带会暴露它们位置的

。