这句话的for which 看不懂

这句话其实是介词+关系词引导的定于从句,是定于从句复杂的一种。这里which指代的先行词the age-range 年龄段,因为是定于从句,主语就是先行词which,你会问for怎么回事,这是因为本句先行词在后面的从句中作介词的宾语,只是这儿吧介词提前了,原句的语序为Children of immigrants would also especially benefit from a larger participation in kindergarten before the age of four,the age-range which provides strong disincentives to send children into early childhood educational institutes for (the age-range)注意括号里就是which代的部分 。 再问： 似乎从语法上这样理解没错，但我个人更倾向于直接把which解释为before the age of four，因此 for which 看成是定语，即 the age-range for before the age of four