The indication can be audible such as a tone or a voice, visual such as a flashing light, or tactile such as vibration.
该指示可以是可听的，比如音调或语音，可以是可视的，比如闪光，或者可以是可用触觉感知的，比如振动。
2
Listen for any audible air leaks, unusual noises, fuel pump buzz (a noisy pump may not be an indication of poor operating condition), engine rattles or knocks. E.