后备军人

例句：

1. 1. The backup system was designed to replace the main system in case of failure.
   备份系统设计用来在主要系统故障时替代使用。
2. 2. The company has a large reserve of cash to cover unexpected expenses.
   该公司拥有大量现金储备，以应对意外开支。
3. 3.The backup plan is ready to go if the main plan fails.
   如果主计划失败，备用计划已准备就绪。