he is working hard for fear that he ___ A should fall behind B would fall behind

题目

he is working hard for fear that he ___ A should fall behind B would fall behind
为什么答案选A
我觉得应该选B 意思是可能会落后,这个should怎么解释?

答案

should 作为情态动词,用在由 so that,for fear that,lest 引导的目的状语从句和 in case （that） 引导的条件状语从句中,有“能够”、“可能”、“会”之意.例如：They got up early so that they should （= could/...