前级真空的英文

• backing space
• backing vacuum
• fore vacuum
• forvacuum
• primary vacuum

• 前:    front
• 级:    level; rank; grade
• 真空:    vacuum; empty space; vacuo
• 前级真空泵:    backing pump; backing vacuum pump; fore pump; fore vacuum pump; forepump; forevacuum pump
• 前级真空表:    forevacuum gauge

例句与用法

1. Backing space technique
   前级真空技术