circuit opening relay  断路继电器

at-the-opening (opening only) order  开盘指令

Opening-Closing-Opening Test  分合分试验

reform and opening-up; reform and opening to the outside world  改革开放

FR-FR Frame Relay – to – Frame Relay  从帧中继到帧中继

phase-rotation relay phase-sequence relay  相序继电器

phase-sequence relay phase-rotation relay  相序继电器

slow-release relay (=slow-releasing relay)  缓释继电器

[endoscopic]biopsy channel opening  弯曲部

2008 Beijing Olympic Ceremony Opening  交流电流

30 years after the Reform and Opening Up  改革开放30年

30 years of Chinese Reform and Opening  中国锦屏地下实验室

30 Years of Reform and Opening  改革开放三十年; 改革开放30周年; 高氯酸铵

30 years of reform and opening-up  改革开放30年

30 years since the introduction of reform and opening up  红紫酸铵; 紫脲酸铵

30 Years’ Reform and Opening  改革开放30年

30 years’ reform and opening-up  改革开放30年

30°tilted opening  30°斜开孔

3-D square opening cavity flow  三维方形开口流