A:when did you see Jack?B:I saw him when I ( ) off the train (get)

这个问题属于时间状语从句的用法，通常时间状语从句
常用引导词：when, as, while, as soon as, before, after, since , till, until
特殊引导词：the minute, the moment, the second, every time, the day，the instant, immediately , directly, no sooner … than, hardly …when, scarcely … when
例句：　　She didn't not show up when all the journalists arrived at the hall.
I didn’t realize how special my mother was until I became an adult.
　 　While John was watching TV, his wife was cooking.
　 　The children ran away from the orchard(果园) the moment they saw the guard.
　 　No sooner had I arrived home than it began to rain.
　 　Every time I listen to your advice, I get into trouble.
所以，你给出的例句的正确的应该使用get的过去形式，got
希望对你有帮助！

got 写句子的最基本原则之一就是：时态要对应！OK？

got