句子 He claims that at Oxford and Cambridge Universities (Oxbridge for short) a few select people start on
an escalator ride which, over the years, carries them to the tops of British privilege and power.
其中的:ride which, over the years, carries them to the tops of British privilege and power.应该是escalator的定语从句吧?可是“动词原形ride +which引导的从句”作定语从句,这是什么语法?查很多语法资料都没有阐述啊,如果没有“动词原形ride”则语法倒是很明白,问题就是多了这个,虽然从字面意思看是明白的,可是没有语法根据呀,还请高手指点啊,都把我给弄糊涂了,谢谢!