But this does not matter,for,as he has often remarked,one is never too old to learn

问题描述:

But this does not matter,for,as he has often remarked,one is never too old to learn
for在这里是什么用法,
为什么用了两个","
为什么for前后都用了“,”

这句话里as he has often remarked是插入语,补充说明,所以as he has often remarked前后都要加逗号隔开.
原话可以改为:But this does not matter,for one is never too old to learn.
但这没关系,因为正如他常说的那样,活到老学到老.