A、l% B、0.5%~l% C、0.3%~0.5% D、0.25%以下
A、l% B、0.5%~1% C、0.3%~0.5% D、0.25%以下
A.絕對(duì)壓力B.相對(duì)壓力C.真空度D.壓力