If you do something beforehand, you do it earlier than a particular event.
例句
How could she tell beforehand that I was going to go out?...她怎么会事先知道我要出去?Saunas can be hazardous if misused. Avoid a big meal beforehand.洗桑拿浴如果方法不当会有危险,浴前切忌饱食。
英汉词典释义
adv.
预先, 事先
Please inform me of your arrival time beforehand.请事先通知我你抵达的时间。
英英词典释义
Adjective
1. being ahead of time or need;
"gave advance warning""was beforehand with her report"
Adverb
1. ahead of time; in anticipation;
"when you pay ahead (or in advance) you receive a discount""We like to plan ahead""should have made reservations beforehand"