Traffic police are sometimes very polite.

问题描述:

Traffic police are sometimes very polite.
sometimes 不是一般放在be动词前吗?这里是为什么

新概念的文章对啊 为什么啊频度副词作状语时,通常放在行为动词之前,情态动词,助动词和be动词之后。例如:She usually gets up early.I’ve never heard him playing basketball.She is seldom ill.