n the sound of knocking (as on a door or in an engine or bearing)
v deliver a sharp blow or push :"He knocked the glass clear across the room"
v rap with the knuckles
v knock against with force or violence
v make light, repeated taps on a surface
v sound like a car engine that is firing too early
v find fault with; express criticism of; point out real or perceived flaws
[机] 爆震内燃机