in advance 是介词短语,中间不加the,在句中作副词用,作方式状语,表示“事先,预先,提前”等意。
例如:
It is desirable that we should read descriptions of particular instruments in advance.
我们最好是事先阅读特殊仪器的说明。
The iron mine fulfilled the state production plan one month in advance.
这个铁矿提前一个月完成了国家生产计划。