The railroad accident was caused by a horse standing on the rails.stand为什么用ing形式?

问题描述:

The railroad accident was caused by a horse standing on the rails.stand为什么用ing形式?

主要是by a horse standing on the rail(由一匹站在铁轨上的马引起),这是一个介词短语,作为was caused(被动语态)的状语.既然是短语不是句子,所以里面的stand就只能用动名词的形式,而不是动词原形.但如果用定语从...