英语翻译You have to be 18 years old before you are allowed to dr

你必须满十八周岁才允许驾驶（车辆）.
时间状语从句.
由 when, while, as, before, after, since, till, until, as soon as, so(as)long as, no sooner...than, scarcely(hardly)...when, once, each time, every time 等引导的皆为时间状语从句.