SIMPLE PAST OR PRESENT PERFECT? 3

GRAMMAR REVIEW: The trickiest simple past vs present perfect cases

You've now done the hardest of our three exercises. Here are the specific cases that trip up even intermediate learners:

1. "For" with simple past vs present perfect
I worked there for ten years. → simple past, I no longer work there.
I've worked there for ten years. → present perfect, I still work there.
The word for alone doesn't tell you which tense to use — the meaning does.

2. Specific past time + present perfect = always wrong
Never use the present perfect with a finished time expression.
❌ I have visited Paris last summer.
✅ I visited Paris last summer.

3. "This week / this year" — it depends
If the time period is still in progress, use present perfect: I've read two books this month.
If the time period is over, use simple past: I read twenty books last year.

4. Stative verbs in the past
Verbs like know, believe, think, and understand usually take simple past when referring to a past state that has changed:
I didn't know you felt that way. ✅ (not "haven't known")