I skated for four hours与I have been skating for four hours的区别最好详细点，说的明白点

I skated for four hours 过去时，过去的某个时间我滑冰滑了四个小时。

I have been skating for four hours 强调已经，我已经滑了四个小时冰。skating，现在还在继续。

前者是曾经某次滑冰滑了四小时。后者是已经滑了四小时，现在仍在继续。