英語の疑問文は、主語と動詞をひっくり返して作ります。be動詞と助動詞はそのまま前へ出ます。一般動詞は前に出られないので、do / does / did を助っ人として呼びます。そして助っ人が時制を引き受けたら、本動詞は原形に戻ります。Did you go? であって Did you went? ではありません。
English builds a question by flipping the subject and the verb. Be and the auxiliaries can move up front on their own. An ordinary verb can't, so it calls in do, does, or did for help. Once that helper takes over the tense, the main verb drops back to its base form: "Did you go?" never "Did you went?"
前に出られる動詞と、出られない動詞
Some Verbs Move, Some Need Help
前に出られるのは be動詞と助動詞(can / will / have など)だけです。like や go のような一般動詞は自力で動けません。そこで do を呼んできて、do に前へ出てもらいます。このとき do は「する」という意味を持たず、語順をひっくり返すためだけに来ています。意味のない助っ人だと考えると、原形に戻る理由も見えてきます。時制の印は do のほうへ移っているからです。
Only be and the auxiliaries — can, will, have and their friends — can move to the front by themselves. Ordinary verbs like like or go can't. So the sentence calls in do, and do makes the trip instead. In that job do carries no meaning of its own; it exists to flip the order. Once you see it as an empty helper, the base form makes sense too, since the tense has moved over to the helper.
3つのパターンThree patterns
Are you free on Friday?
金曜は空いてる?
be動詞は自力で前へ。do は要らない。Be moves on its own. No do required.
Can you send it by noon?
正午までに送ってもらえる?
助動詞も自力で前へ。後ろは原形のまま。An auxiliary moves on its own too, and the base form follows it.
Did you send theなぜ the なのか【その場で一つに決まる】話し手と聞き手のいる状況で、どれを指すか一つに決まるから the。日本語なら「（例の）」「うちの」を補って読むと感覚が近い。 invoice?
請求書は送った?
一般動詞なので did を呼ぶ。send は原形に戻る。An ordinary verb, so did steps in and send returns to its base form.
自力で前に出る(be・助動詞)
そのまま主語の前へ移動する。形は変わらない。Moves straight in front of the subject, unchanged.
Is she coming?
彼女は来るの?
Have you eaten?
もう食べた?
助っ人を呼ぶ(一般動詞)
do / does / did が前へ出て時制を引き受け、本動詞は原形に戻る。Do, does, or did goes up front and takes the tense; the main verb goes back to base.
Does she come here often?
彼女はよくここに来るの?
よくある間違い / Common Mistake
×Did you went to the office yesterday?
きのう会社に行った?(のつもりで)
○Did you go to the office yesterday?
きのう会社に行った?
過去の印が2つ入っています。did がすでに過去を示しているので、went を重ねる必要はありません。英語の決まりは単純で、時制の印は文にひとつだけ。同じことが三人称にも当てはまります。Does she comes? ではなく Does she come?。does が -s を引き受けたので、本動詞は原形に戻ります。
Two past-tense markers have crept in. Did already carries the past, so went is doing the job a second time. The rule is short: one tense marker per clause. The same applies in the third person. Write "Does she come?" not "Does she comes?" — the does has taken the -s, so the main verb returns to base.
How come ...?なんで〜なの?why と同じ意味だが倒置しない。How come you didn't call? が正しい形。Means why but takes no inversion: "How come you didn't call?" is the correct shape.
Do you happen to know ...?ひょっとしてご存じですかhappen to を挟むと当たりがやわらぐ。道を尋ねるときの定番。Slipping in happen to softens the ask. A staple when stopping a stranger.
Any chance you could ...?〜してもらったりできる?文頭を省いたくだけた依頼。倒置を使わずに疑問を出す型。A clipped, casual request that gets a question across without inverting anything.
What's it like?どんな感じ?様子を尋ねる定型。like は「〜のような」で、好き嫌いの like ではない。The set way to ask what something is such as. This like means similar to, not enjoy.
まとめ / Summary
be動詞と助動詞は自力で前に出る。Be and the auxiliaries move to the front by themselves.
一般動詞は do / does / did を助っ人に呼ぶ。Ordinary verbs call in do, does, or did.
助っ人が時制を引き受けたら、本動詞は原形。Once the helper takes the tense, the main verb returns to its base form.
時制の印は文にひとつだけ。One tense marker per clause, no more.