Fifteen million tress have been blown down by hte windstorm,____(block) roads and railway lines.
问题描述：
Fifteen million tress have been blown down by hte windstorm,____(block) roads and railway lines.
答
blocking.
这是一个状语从句,因为树被刮倒了,所以它阻断和公路和铁路.前面已经是完整的句子,所以后面的句子只能是做一个成分,修饰前面的部分.