“Ancient people didn’t know” is a thing in the past, so we use past tense to say it.
“The earth moves around the sun” is a fact that doesn’t change, so we use present tense.
You cannot use past perfect tense, which is standing at a previous point to look at something earlier, in place of these two tenses in these sentences.
Past perfect: I had finished my homework before I go out.
Present perfect: I have been to that place for 10 times. (Present perfect is also a common tense. It’s used when you want to say something you have already done until now.)
なるほど！最初のI had finished my homework before I go out. はなぜhaveではなくhadなんですか？
学校では文章を書く時haveより昔の話にはhadを使うと聞きました
I go outにはhaveは使わないんですか？
Oh, Sorry. It should be “I had finished my homework before I went out.”
haveは使わないんですか？🥲
“have + past participle” is present perfect tense. There is three main usages of this tense:
1. Has accomplished something so far. Ex. I have washed the dishes. Ex. I have finished my homework.
2. Experienced so far. Ex. I have been to that place for 10 times.
3. An action continues from the past to the present:. Ex. I have lived in that place for 10 years.
“had + past participle” is past perfect tense. The usage is:
1. Standing at a previous point to look at something earlier than the point. Ex. I had finished my homework before I went out.
When using present perfect tense, it’ll be “I have finished my homework.” When using past perfect tense, it’ll be “I had finished my homework before I went out.”
では過去完了や完了形の例文を教えてくれませんか😭