Qual è la differenza tra I was walking through the park e I was walking across the park ?Sentiti libero di rispondere con un esempio.

It's difficult to explain because it can change from sentence to sentence.

"through the park" to me would mean that you're IN the park and you're moving inside the park, not necessarily to leave it. So if you're "walking through the park", then that could be an activity of its own or it could be a way of getting to another place.

"across the park" to me would mean that you're OUTSIDE of the park and you walk in it to walk to the other side of the park, as a way of getting to someone else. "walking across the park", therefore, isn't an activity in itself, it's just a way to get to somewhere else.