时间状语从句，条件句中，从句用一般现在时代替将来时
When, while, before, after, till, once, as soon as, so long as, by the time, if, in case , unless, even if, whether, the moment, the minute, the day, the year, immediately
He is going to visit her aunt the day he arrives in Beijing. 他一到北京，就去看他姨妈。
典型例题
表示现在已安排好的未来事项，行程等活动。
The museum opens at ten tomorrow. 博物馆明天10点开门。