Cars are to Americans what bikes are to Chinese.为什么用what链接,而不用that/which/whether?what

Cars are to Americans what bikes are to Chinese.为什么用what链接,而不用that/which/whether?what
Cars are to Americans what bikes are to Chinese.
为什么用what链接,而不用that/which/whether?what

Cars are to Americans what bikes are to Chinese.为什么用what链接,而不用that/which/whether?what
A is to B what C is to D 固定用法,表示"A对于B相当于C对于 D".What在这里没有实在意义,只是用于构成这个固定结构

s + v ..., what + s + v... 如同... 一样 (adv子句的从属连接词)
Air is to man what water is to fish.空气之於人 犹如水之於鱼一样
Air is to man as water is to fish.
What water is to fish, that air is to man.