periodical backup的用法和樣例：
例句
- The system includes a backup auxiliary system.
此系統還有一個後備的輔助系統。 - In local backup relaying, faults are cleared locally in the same station where the failure has occurred.
在近後備繼電器中，故障在失效已經發生的相同的地方被地切除的。
辭彙搭配
- back up (因積聚而)擁堵...
