The boost stage is a centrifugal-type pump. The main stage is a gear-type pump. The above sentence means "增压级泵是一个齿轮式泵，主要级泵是一个离心式泵．"
A.1
正确答案是B
The boost stage is a centrifugal-type pump. The main stage is a gear-type pump. The above sentence means "增压级泵是一个齿轮式泵，主要级泵是一个离心式泵．"
A.1
正确答案是B