1.As fluid is evacuated from the system or vessel, the vent valve must open to prevent formation of a vacuum.
当流体从系统或容器中排空时，排放阀必须打开以防止出现真空现象。
2.Prevent Formation in the First Place
首先要避免形成？
3.Study on drilling fluid for horizontal well to prevent formation damage in Minghuazhen formation, CB 243 block
埕北243区块明化镇组保护油层的水平井钻井液研究