[] a system of cheap tickets for train or air travel if you buy your ticket a particular number of days before you travel 预付款旅游票优惠（旅游前若干天购买火车票、飞机票等而享受的票价优惠）◆Apex fares/tickets 预付款旅游票价／票ⓘ Apex is the short form for ‘advance purchase excursion’. Apex 是 advance purchase excursion 的缩写。