这句翻译不知道怎么处理,请大家指教!pitting of valve? where practical 实际可行时, roll转动,启动 ? drop out 松脱,脱离,退出 ? debris碎屑 pitting麻点,凹坑 where practical "roll" or "drop-out" all control valves to prevent pitting of the valve seats due to deposition of debris on the seat. 实际可行时,要转动或松脱所有控制阀,以防阀座上有碎屑而导致表面出现凹坑。 roll和drop-out应该是接近的含义还是相反的含义呢?熟悉阀门的多来说几句。查看更多