Not "I have seen him yesterday." — say "I saw him yesterday.". Yesterday 是已结束、说得出来的具体时间，所以用一般过去式：saw，不用 have seen。
试一试: Hiroshi 在讲他去 Senfarren 的那次旅行。那是前年夏天的事，早就结束了。 哪个更符合他在某个具体时间已经结束的旅行？ (He visited the old castle. / He has visited the old castle.) 答案: He visited the old castle. — 这次旅行已经结束，而且有具体的时间（two summers ago），所以用一般过去式：He visited。"He has visited" 是用在不把它跟具体已结束的时间挂钩的时候。
试一试: Finish it with the past participle of work: "They have ___ here for a year." (worked / work / working) 答案: worked — Work 是规则动词，过去分词直接加 -ed：worked。
Not "I have saw that film." — say "I have seen that film.". have / has 后面要用过去分词（seen），绝不能用一般过去式（saw）。
试一试: Finish it with the past participle of eat: "She has ___ sushi before." (ate / eaten / eat) 答案: eaten — has 后面要用过去分词，而 eat 是不规则的：eat → eaten。"Ate" 是一般过去式，"eat" 是动词原形——这两个都不能跟在 has 后面。
该用 have 还是 has？
看句子说的是谁，来选 have 还是 has：I / you / we / they → have；he / she / it → has。然后接过去分词。缩写形式：I've, you've, we've, they've 和 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 永远用 has，不用 have。
试一试: Finish it with know: "My friends ___ me for years." (have known / has known / knows) 答案: have known — "My friends" 相当于 they，而 they → have，后面接过去分词：have known。has 只用于 he / she / it，所以 "has known" 在这里不合适。
不说时间，只谈人生经历：have / has done
当你不说具体是什么时候，只是想表达人生中某个时候做过，用 have / has + 过去分词。
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.
试一试: Mei 在泛泛地聊自己的经历，没有说任何一件事是什么时候发生的。 哪个更符合没有说明具体时间的经历？ (She has eaten Japanese food. / She ate Japanese food.) 答案: She has eaten Japanese food. — 她只是想表达人生中某个阶段发生过，没有说具体时间，所以用 has eaten。"She ate" 会让人以为有个已结束的具体时间，比如 "yesterday"，但她并没有给出这样的时间。
从过去开始，现在仍然如此：have / has done
当某件事从过去开始，一直到现在都还是这样，用 have / has + 过去分词（常常搭配 for 或 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.". 这件事从过去开始，到现在依然如此，所以用 have lived，不用一般过去式。
试一试: Amina 几年前搬到了 Haffenville，到今天还住在这里。 哪个更符合从过去开始、到现在依然如此的情况？ (She has lived here for years. / She lived here for years.) 答案: She has lived here for years. — 她从过去开始，到现在依然住在这里，所以用 has lived。"She lived here for years" 听起来像是已经结束了，好像她已经搬走了，但她其实还住在这里。
否定，以及提问
要说否定，在 have/has 后面加 not——通常缩写成 haven't（have not）或 hasn't（has not）——再接过去分词。要提问，用 Have 或 Has 开头：Have you ever been…? · Has she eaten…?ever 的意思是 at any time in your life（人生中的任何时候）。简短回答：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?". have/has 的疑问句要用 Have / Has 开头——不要再加 do / does。
试一试: 把单词排好顺序，问 Lars 关于他整个人生的经历。 答案: Has he ever played football? — have/has 的疑问句用 Has 开头：Has he ever played football? 不要再加 "Does"——have/has 本身就已经构成疑问句了。
试一试: Make it negative with be: "He ___ to Senfarren." (hasn't been / haven't been / hasn't be) 答案: hasn't been — He → has，而 has + not = hasn't；be 的过去分词是 been。所以是：hasn't been。"Haven't" 是给 I/you/we/they 用的，"hasn't be" 则少了过去分词。
该用哪个？快速判断法
问问自己：有没有一个说得出来的、已结束的时间（yesterday、last week、in 2019）？如果有 → 一般过去式（saw、went、played）。如果没有说出时间，或者这件事从过去开始、到现在依然如此 → have / has + 过去分词（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" 是说得出来的已结束时间，所以用一般过去式：saw。
试一试: Lars 在跟你讲上周六的事。比赛就是那天踢的，已经结束了。 有人问 Lars 有没有踢过足球。他在讲自己的经历，没有说具体时间。 把每一句配对起来。哪种形式符合哪个时刻？ 答案: Lars 在跟你讲上周六的事。比赛就是那天踢的，已经结束了。 → 1 → He played in the match. · 2 → He has played many times. 有人问 Lars 有没有踢过足球。他在讲自己的经历，没有说具体时间。 → 1 → He has played in the match. · 2 → He played many times. — 在具体已结束的时间（last Saturday）发生的比赛 → 一般过去式：He played。没有说明具体时间的人生经历 → has played。有没有说出已结束的具体时间，决定了这两句该怎么选。