Gate keeps closely movement with gate when opening and closing, makes valve open and close stability and cuts off the media, and so on.
在关闭和开启过程中阀座跟闸板一直紧贴运动，使得阀门启闭力稳定，并且具有切断介质等特点。
2
Mathematic analysis is a course of studying function by limit method with dialectical closing thought of movement as its basic idea and limit theory as its basic tool.