Which is correct
1. He has completed the race.
2. He completed the race.
Both are correct. ^0^
What's the context?
Using HAVE makes this one of the PERFECT tenses.
I HAVE completed the race, I HAVE talked to my boss about my vacation.
He HAS gone home, he HAS fallen asleep.
You HAVE, we HAVE, they HAVE, etc.
What is the difference between the SIMPLE PAST tense and the PERFECT tenses?
You use PERFECT tenses when the thing that happened in the past is connected/related/is finishing in the PRESENT.
You use the SIMPLE PAST tense when the action happened in the past and IS NOT related to/connected to the PRESENT.
My brother fell asleep.
My brother has fallen asleep.
My brother fell asleep.. maybe ten years ago, maybe a year ago, no one knows. "When he was a baby he fell asleep and fell out of bed." Action in the past, and HAS NOTHING TO DO WITH TODAY.
My brother has fallen asleep... means he is STILL asleep NOW, or, for some reason, we care about it TODAY.
"My brother has fallen asleep, be quiet." "My brother has fallen asleep many times today." "My brother has fallen asleep before when he was sick, he might do it again."
Sometimes it is hard to know if the PAST action is CONNECTED to today... and you need to use the PERFECT tense.
But if it is only a story about the past, use SIMPLE PAST... but if the old action MATTERS today, use the PERFECT tenses.
The man walked down the street. He saw a bird. The bird chirped at him.
(In the past, old story, no connection to today.)
The man has walked down the street before. (And he might do it again.)
He has seen a bird. (Maybe just one minute ago. Or maybe, he wants to see it again. OR, he always remembers that bird, he remembers him today.)
I have seen Tokyo... (It makes me happy to think about it today.)
The bird has chirped at him. (The bird has chirped at him, and might chirp at him again.)
He has completed the race.. five minutes ago. He has completed the race and is thinking about running it again. OR He has completed the race, and NOW he believes he will never run it again.
He completed the race. Then he ate lunch. He saw a bird after the race. All long ago, no connection with today.