When it comes to Past Simple and Present Perfect, I like to give the old example which goes as follows:
- This man has never seen sea.
- This man never saw sea.
What's the difference between the two sentences? The first one means the man hasn't had a chance to see sea. Well, maybe he is poor and just can't afford a trip... anyway, you can see that we're now talking about USE 3 "Actions which began in the past and continue in the present".
The second sentence is much different. The combination of "never" and past tense of "see" tells the listener that the action is finished -- the man is in a better place.
When it comes to Past Simple and Present Perfect, I like to give the old example which goes as follows:
- This man has never seen sea.
- This man never saw sea.
What's the difference between the two sentences? The first one means the man hasn't had a chance to see sea. Well, maybe he is poor and just can't afford a trip... anyway, you can see that we're now talking about USE 3 "Actions which began in the past and continue in the present".
The second sentence is much different. The combination of "never" and past tense of "see" tells the listener that the action is finished -- the man is in a better place.
I hope that helps,
Mark