后备的

例句：

1. 1. The server is down for maintenance, so we need to have a backup plan in place.
   服务器正在维护，所以我们需要有一个备用计划。
2. 2. The software developer had to back up his work before moving it to another computer.
   软件开发人员在将工作转移到另一台电脑之前，必须备份他的工作。
3. 3.We should always have a backup of our important documents in case of emergency.
   我们应该总是有重要文档的备份，以防万一。