You'll never get to college to find out, Robbie,
你根本就进不了大学去探究这个问题的答案 ,Robbie,
Precautions of this sort are necessary, for it is impossible to foretell the exact nature of the difficulties which will confront the pot-holer.
作出这样的准备是必要的,因为无法预见到洞穴探险者究竟会遇到什么性质的困难。