不及物动词

1. (使)咔嗒作响;(使)啪啪作响
If things clack or if you clack them, they make a short loud noise, especially when they hit each other.

1. a simple valve with a hinge on one side
allows fluid to flow in only one direction

Synonym: clack valveclapper valve

2. a sharp abrupt noise as if two objects hit together
may be repeated

Synonym: clap