This lesson is mostly a reinforcement on previous topics, the main focus being understanding the difference between Present Perfect, and Past Simple.

What’s the difference?

Present Perfect Past Simple
Unfinished actions that started in the past and continue in the present: I’ve known julie for ten years (and I still know her). Finished actions: I knew julie for ten years (but then she moved away and we lost touch).
A finished action in someone’s life (when the person is still alive; A life experience.): My brother has been to mexico three times. A finished action in someone’s life (when the person is dead): My great grandmother went to Mexico three times.
A finished action with a result in the present: I’ve lost my keys! (Now I can’t get into my house). A finished action with no result in the present: I lost my keys yesterday. It was terrible! (I also got a new pair of keys yesterday, there’s no result).
_With an unfinished time word (this week, this month, today): I’ve seen John this week. With a finished time word (yesterday, last week, last month): I saw John last month.

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