【一道英语完型】高手进!the drivers of _were constanly
问题描述：
【一道英语完型】高手进!the drivers of _were constanly
There was not enough room for all the people on the sidewalk at the roadside,and they overflowed into the road,causing danger to their lives from passing cars and buses,the drivers of (which )were constantly blowing their horns (喇叭) to persuade people to get out of their way.
为什么要用which 不能用them them指代的是cars and buses,为什么不可以
答
这是一句定语从句,如果要用them,那前面不是逗号,一定要用and连接,这是个很重要的语法点,需要记住.先行词是cars and buses 对吧？ 还原到句子放在什么位置？the drivers of之后