fixed window

例句：

1. 1. The plan is fixed and cannot be changed.
   这个计划是固定的，不能更改。
2. 2. The weather is fixed for the next few days.
   接下来的几天天气固定不变。
3. 3. The team's strategy is fixed;there's no room for error.
   团队的策略已经确定，没有错误空间。