boom-retraction mechanism伸缩: stretch out and draw back; e ...套管: drivepipe; annular tubes; br ...机构: mechanism伸缩套管收藏指示器: boom stowed indicator可伸缩套管: telescopic tube下载手机词典可随时随地查词查翻译关注微信公众号：chachacidian，回复:伸缩套管收放机构，即可在微信中查询翻译
