stand-by set

例句：

1. 1. The engineers are standingby to fix the leaky pipe.
   工程师们随时待命，准备修理漏水的管道。
2. 2. The fire department has a stand-by set of equipment ready in caseof emergencies.
   消防部门有一套备用设备，以备不时之需。
3. 3.The construction team is working on a stand-by set of plans for the newproject.
   建筑团队正在为新项目准备一套备用计划。