Valve number 2 is awkward to maintain, as its spring return actuator is heavy and causes unnecessary strain on the pipe elbow just above it before the pipe turns downward through the floor.是什么意思_Valve number 2 is awkward to maintain, as its spring return actuator is heavy and causes unnecessary strain on the pipe elbow just above it before the pipe turns downward through the floor.在線(xiàn)翻譯_英語(yǔ)_讀音_用法_例句