on line maintenance

例句：

1. 1.The website is currently undergoing on-line maintenance.
   该网站目前正在进行在线维护。
2. 2. We need to schedule an on-line maintenance appointment for our server.
   我们需要安排一个服务器的在线维护预约。
3. 3. The company has implemented a new system for on-line maintenance.
   该公司已经实施了一个新的系统来进行在线维护。