for通常可以接一段时间，而不能接点时间。

常和现在完成时连用，有时也可以和一般将来时、一般过去时连用。since后面才可以接点时间

相关介绍

I have learned English for one score years.

I haven't seen you for ages.

He has studied Chinese for thirteen years.

He has played the piano for two hours.