短语词组短语diaphragm valve spring seat [铁路]膜片阀弹簧座valve -seat cutter 气门座铣刀valve spring seat pin 气门弹簧座销ventilator valve spring seat 通风阀簧座butterfly valve valve seat 蝶阀阀座Safety valve spring seat 安全阀弹簧座 返回 valve seat