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

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/...