求before的各种用法 越详细越好

before

adv
at an earlier time; in the past; already 以前; 过去; 已经:
You should have told me so before. 你早就应该告诉我.
* It had been fine the day/week before, ie the previous day/week. 前一天[一周]天气很好（以过去某时为准的前一天[一周]）.
* That had happened long before, ie a long time earlier. 那事老早就发生了（比过去某时早得多）
. * I've seen that film before. 我以前看过那部影片. =>Usage at before2 用法见before2. Cf 参看 after1, afterwards.

prep

1 earlier than (sb/sth) 早於（某人[某事物]）; 在（某人[某事物]）以前: before lunch 午餐前 * the day before yesterday 前天
* two days before Christmas 圣诞节的前两天
* The year before last he won a gold medal, and the year before that he won the silver. 他前年赢得一枚金牌, 大前年赢得一枚银牌.
* She's lived there since before the war. 她从战前就一直住在那里.
* He arrived before me. 他在我之前到达.
* He taught English as his father had before him. 他教过英语, 他父亲以前也教过英语.
* Something ought to have been done before now. 早就该采取措施了. * We'll know before long, ie soon.