Present Perfect Vs Simple Past

Present Perfect Uses

Finished actions:

1. Indefinite past

a) Exact time is unknown or unimportant, emphasis on achievement (how many things you did, how many times you did it); time period is unfinished:

I’ve taught at many universities.

I’ve written three letters today.

I’ve been to many interesting cities.

b) With just, recently, and lately to indicate something happened in the very recent past:

We’ve recently realized that we need to make some changes.

He’s just returned from his trip.

I haven’t had time to do anything fun lately.

c) With ever to ask if something has happened at any time before now:

Have you ever seen a cow fly?

Have you ever met my mother?

2. Present perfect + since

Some completed action happened between a point in the past and now:

Now

Jon has written 2 books since he graduated from college.

3. Present perfect + already and yet

Something happened before now:

Have you seen that movie yet?

Yes, I’ve already seen it.

Now

I’ve already seen the movie.

Jon graduated from college. Jon wrote a book. Jon wrote another book.

Unfinished actions:

1. Present perfect + for or since

The action began in past and continues up to present (use with non-action verbs in place of present perfect

progressive)

Joe has had the dog since 1995.

Joe has been a student since 1995.

Simple Past Use:

Finished actions in finished time periods:

I lived in Paris for two years.

I graduated from high school.

I visited many interesting cities when I was a child.

John graduated from college in 1999.