1. Present Perfect vs Simple Past
Lesson 8

2. Present Perfect Used for events in the past at no specific time.
Have you ever been in London?
Used to stress the importance of the effect in the present, that is the reason is called PRESENT PERFECT.
I have graduated from college.
Used to talk about duration of events.
What matters is the event itself not the time when it ocurred.
It is possible to change the situation.

3. Simple past Used for events in the past at a specific time.
Did you go to London? (when?)
What matters is when it ocurred.( in the past)
It isn’t possible to change the situation.
It’s a finished event.