reserve back-up
These front-line defences are backed up by armoured units in reserve.
前线的防务得到后备装甲部队的支援。
—— 柯林斯例句You are hereby appointed Sub-Lieutenant RNVR of HMS Tartar.
你被任命为皇家海军舰艇“鞑靼人”号的皇家海军志愿后备队中尉。
—— 柯林斯例句-- There is also potential for exploiting untouched arable land resources.
-- 开发后备耕地资源有潜力。
—— 给力词典精选When the main system fails, the backup system take over.
当主系统不能工作时, 后备系统立即投入工作代替之。
—— 辞典例句John made the second string on the football team.
约翰成了该足球队的后备队员。
—— 辞典例句