When the time is finished and you name it (yesterday, last week, in 2019), use the plain past form.
A finished time you name: the past form
I saw that film last week.
She went to Senfarren in 2019.
We met them yesterday.
Not "I have seen him yesterday." — say "I saw him yesterday.". Yesterday is a finished, named time, so use the plain past: saw, not have seen.
Try it: Hiroshi is talking about his trip to Senfarren. He took it two summers ago, and it is over. Which fits a finished trip at a time he names? (He visited the old castle. / He has visited the old castle.) Answer: He visited the old castle. — The trip is finished and set at a named time (two summers ago), so use the plain past: He visited. "He has visited" is for when you do not tie it to a finished time.
The past participle (what comes after have / has)
You already build the past participle the same way: most verbs just add -ed — play → played, work → worked, visit → visited. That does not change here. What this lesson adds is knowing when to use it instead of the plain past form.
play → played
work → worked
visit → visited
Try it: Finish it with the past participle of work: "They have ___ here for a year." (worked / work / working) Answer: worked — Work is regular, so the past participle just adds -ed: worked.
Irregular past participles
Some common verbs don't take -ed. Learn these by heart: see → seen, eat → eaten, know → known, go → gone, be → been, meet → met.
see → seen · eat → eaten · know → known
be → been · meet → met · go → gone
Not "I have saw that film." — say "I have seen that film.". After have / has, use the past participle (seen), never the plain past (saw).
Try it: Finish it with the past participle of eat: "She has ___ sushi before." (ate / eaten / eat) Answer: eaten — After has you need the past participle, and eat is irregular: eat → eaten. "Ate" is the plain past and "eat" is the base verb — neither one works after has.
have or has?
You already pick have or has by who the sentence is about: I / you / we / they → have; he / she / it → has, then the past participle. Short forms: I've, you've, we've, they've and he's / she's / it's.
I have seen it. · You / We / They have seen it.
He has seen it. · She has been there. · It has happened.
Short forms: She's been to Senfarren. · They've met before.
Not "She have eaten sushi." — say "She has eaten sushi.". he / she / it always takes has, not have.
Try it: Finish it with know: "My friends ___ me for years." (have known / has known / knows) Answer: have known — "My friends" = they, and they → have, then the past participle: have known. Use has only with he / she / it, so "has known" does not fit here.
No time, just your life so far: have / has done
When you do not say when, and you just mean at some point in your life, use have / has + the past participle.
I have seen that film. (at some time, doesn't matter when)
She has been to Senfarren. (in her life)
We have met them before.
Try it: Mei is talking about her life in general. She does not say when anything happened. Which fits an experience with no time named? (She has eaten Japanese food. / She ate Japanese food.) Answer: She has eaten Japanese food. — She just means at some point in her life, with no time named, so use has eaten. "She ate" would make you expect a finished time, like "yesterday", which she does not give.
Started before, still true now: have / has done
When something started in the past and is still true now, use have / has + the past participle (often with for or since).
I have lived here since 2020. (and I still live here)
She has worked there for five years. (and still works there)
We have known them for a long time.
Not "I lived here since 2020." — say "I have lived here since 2020.". It started before and is still true, so use have lived, not the plain past.
Try it: Amina moved to Haffenville a few years ago. She still lives here today. Which fits something that started before and is still true? (She has lived here for years. / She lived here for years.) Answer: She has lived here for years. — She started before and still lives here now, so use has lived. "She lived here for years" sounds finished, like she has moved away, but she is still here.
Saying no, and asking questions
To say no, add not after have/has — usually shortened to haven't (have not) or hasn't (has not) — then the past participle. To ask, start with Have or Has: Have you ever been…? · Has she eaten…? The word ever means at any time in your life. Short answers: Yes, I have. / No, I haven't.
I haven't seen that film. (= I have not seen it)
She hasn't been to Senfarren.
Have you ever eaten sushi? — Yes, I have. / No, I haven't.
Not "Do you have seen that film?" — say "Have you seen that film?". For a have/has question, start with Have / Has — don't add do / does.
Try it: Put the words in order to ask Lars about his whole life. Answer: Has he ever played football? — A have/has question starts with Has: Has he ever played football? Don't add "Does" — the have/has form already turns it into a question.
Try it: Make it negative with be: "He ___ to Senfarren." (hasn't been / haven't been / hasn't be) Answer: hasn't been — He → has, and has + not = hasn't; then the past participle of be is been. So: hasn't been. "Haven't" is for I/you/we/they, and "hasn't be" is missing the past participle.
Which one fits? A quick test
Ask yourself: is there a finished time you can name (yesterday, last week, in 2019)? If yes → plain past (saw, went, played). If no time is named, or it started before and is still true now → have / has + past participle (have seen, has played).
Named finished time? We met in 2019. → plain past.
No time, just life so far? We have met before. → have + past participle.
Started before, still true? I have known her for years. → have + past participle.
Not "I have seen it last week." — say "I saw it last week.". "last week" is a named, finished time, so use the plain past: saw.
Try it: Lars is telling you about last Saturday. The match happened then and is over. Lars is asked if he has ever played football. He talks about his life, with no time named. Match each one. Which form fits each moment? Answer: Lars is telling you about last Saturday. The match happened then and is over. → 1 → He played in the match. · 2 → He has played many times. Lars is asked if he has ever played football. He talks about his life, with no time named. → 1 → He has played in the match. · 2 → He played many times. — A finished match at a named time (last Saturday) → the plain past: He played. A life experience with no time → has played. The named, finished time decides the first; the open life-so-far decides the second.