Cars and buses moved along slowly,their lights on and their horns blaring.
问题描述：
Cars and buses moved along slowly,their lights on and their horns blaring.
这句话中的along作副词吗?还有这里的their lights on and their horns blaring是作定语吗?所以on前才没有加be
答
对,along这里是副词；
their lights on and their horns blaring.这里是伴随状语,也就是说是状语.