do / does / did の3兄弟
do現在形（I, You, We, They）── Do you play?
does三単現（he, she, it, Mark）── Does she play?
did過去形（すべての主語）── Did you play?
過去形のいい点は、主語が誰でも did を使うこと。三単現のときの doesn't / does のように主語ごとに分けなくてよいので楽です。
否定文：did not（didn't）+ 動詞の原形
普通I played tennis yesterday.
否定I did not play tennis yesterday.
短縮I didn't play tennis yesterday.
- did を使った時点で、後ろの動詞は 原形。
- ×I didn't played tennis. → ○ I didn't play tennis.
- 過去の意味は did が背負っているので、動詞は原形でOK。
例文：
- I didn't go to school yesterday. ── 私は昨日学校に行かなかった。
- She didn't eat breakfast. ── 彼女は朝食を食べなかった。
- We didn't see the movie. ── 私たちはその映画を見なかった。
- Mark didn't read the book. ── マークはその本を読まなかった。
疑問文：Did を文の先頭に
普通You played tennis.
疑問Did you play tennis?（did は先頭、play は原形）
Did ...? に答える
- はい → Yes, 主語 + did.
- いいえ → No, 主語 + didn't.
例：
- Did you read the book? ── あなたはその本を読んだ？
── Yes, I did. / No, I didn't. - Did Mark go to school yesterday? ── マークは昨日学校に行った？
── Yes, he did. / No, he didn't.
What did you ...? ──「何を〜したの？」
What疑問文も Did を使うパターンがあります。
①What did you do? ── 何をしたの？
②Where did you go? ── どこへ行ったの？
③When did you come? ── いつ来たの？
④What did you eat? ── 何を食べたの？
語順は 疑問詞 + did + 主語 + 動詞の原形 + ?。What疑問文や Where疑問文の 過去形バージョンです。
例文と答え方
- What did you do yesterday? ── 昨日何をした？
── I played tennis.（テニスをしました） - Where did you go last week? ── 先週どこへ行った？
── I went to Kyoto.（京都に行きました） - What did you eat for breakfast? ── 朝食に何を食べた？
── I ate toast.（トーストを食べました）
新しい疑問詞：When（いつ）と Why（なぜ）
Lesson 7 では、これまで出てきた What/Where/Who に加えて When（いつ）と Why（なぜ）が登場します。
What何 ── What did you eat?
Whoだれ ── Who is that?
Whereどこ ── Where did you go?
Whenいつ ── When did you come?
Whyなぜ ── Why did you go?
Why の答え：Because ...
「なぜ？」と聞かれたら、Because（〜だから）で答えます。
- Why did you go to Kyoto? ── なぜ京都へ行ったの？
── Because I wanted to see kiyomizu-dera.（清水寺を見たかったから） - Why do you like math? ── なぜ数学が好き？
── Because it's fun.（楽しいから）
do / does / did の使い分け 総合表
| 普通文の動詞 | 否定文 | 疑問文 | |
|---|---|---|---|
| I/You/複数 現在 | play（原形） | don't play | Do you play? |
| 三単現 | plays（s） | doesn't play | Does he play? |
| 過去（全主語） | played（過去形） | didn't play | Did you play? |
普通文では動詞の形が違うが、否定・疑問文では3つとも動詞は原形。do/does/did に過去・三単現の情報を背負わせる。
練習問題
英語で使えるようにする練習
この単元は、説明を読んで終わりにすると定着しません。次の型を、主語・時・目的語を入れ替えながら声に出してください。
Did you watch TV?
I did not play tennis.
Where did she go?
- did を使ったら watched ではなく watch。
- 否定文は did not / didn't + 原形。
- 疑問詞があっても did の位置は変わらない。
- I played soccer yesterday.
- She went to Tokyo last week.
答えを見る
(1) I played soccer yesterday.
- 否定：I did not play soccer yesterday.（短縮：I didn't play soccer yesterday.）
- 疑問：Did you play soccer yesterday?
(2) She went to Tokyo last week.
- 否定：She didn't go to Tokyo last week.
- 疑問：Did she go to Tokyo last week?
- あなたは昨日何をしましたか？ ── ( do / yesterday / what / you / did )?
- マークはどこに行きましたか？ ── ( go / Mark / where / did )?
- あなたはなぜ泣いたの？ ── ( cry / why / did / you )?
答えを見る
(1) What did you do yesterday?
(2) Where did Mark go?
(3) Why did you cry?
- Did you read the book?（Yes）
- Did she go to school yesterday?（No）
- What did you do last Sunday?（played tennis）
- Why did you go to Kyoto?（saw a temple）
答えを見る
(1) Yes, I did.
(2) No, she didn't.
(3) I played tennis.
(4) Because I wanted to see a temple.（または Because I saw a temple.）
- I didn't went to school.
- Did she ate breakfast?
- What you did yesterday?
答えを見る
(1) I didn't go to school. ── didn't のあとは原形。
(2) Did she eat breakfast? ── Did のあとは原形。
(3) What did you do yesterday? ── 「did + 主語」の語順。
- あなたはテレビを見ましたか。
- 私はテニスをしませんでした。
- 彼女はどこへ行きましたか。
答えを見る
(1) Did you watch TV?
(2) I did not play tennis.
(3) Where did she go?
まとめ
- 過去の否定文：did not（didn't）+ 動詞の原形。例 I didn't play tennis.
- 過去の疑問文：Did + 主語 + 動詞の原形？ 例 Did you play tennis?
- 応答：Yes, 主語 + did. / No, 主語 + didn't.
- did を使ったら、後ろの動詞は 必ず原形。
- What/Where/When/Why + did + 主語 + 動詞の原形 で、過去の具体的な内容を聞ける。
- Why の答えは Because（〜だから）で始める。
- do / does / did は 主語と時制で使い分ける3兄弟。否定・疑問文では3つとも動詞は原形に戻す。