"之内"在英语中通常表示为 "within"。
来源："within" 是由中古英语 "wiðinnan" 演变而来的，其中 "wiðinnan" 是由 "wið"（表示 "向里面"）和 "innan"（表示 "在内部"）组成的。
例句：
He completed the project within the deadpne. (他在截止日期之内完成了项目。)
The store is open from 9am to 5pm within the weekdays. (商店周一至周五9点到5点营业。)
I will try to finish this book within the next few days. (我会尽量在接下来的几天内读完这本书。)