time limit
noun [ C usually singular ] uk/ˈtaɪm ˌlɪm.ɪt/ us/ˈtaɪm ˌlɪm.ɪt/
时限，期限
the greatest length of time someone is allowed to spend doing something
We've set a time limit of ten minutes for each child's turn on the trampoline. 我们限定每个孩子在蹦蹦床上只能玩10分钟。
There's a 3-hour time limit on Internet use in the library. 图书馆里的互联网使用限时为三小时。