standby valve

例句：

1. 1.The engineers are standing by 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 backup generator is ready to power the hospital in case of a power outage.
   备用发电机已经准备好在停电时为医院供电。
3. 3.The fire department has a standby valve for quick response in case of an emergency.
   消防部门备有备用阀门，以便在紧急情况下迅速响应。