The village is far away from here indeed.It's a four hours' walk.

问题描述:

The village is far away from here indeed.It's a four hours' walk.
为什么有a 可是这是2004年上海春高考,冠词不是不与限定词a,像this,my,等等

没错的,语法上是通的.four hours' walk 是一组名词