did

過去形の疑問文と否定文には did を使います。「過去」の印は did が持つので、後ろの動詞は -ed の付かない原形（go、see、work）に戻ります。did はどの主語でも同じです。日本語では「〜しましたか」「〜しなかった」と動詞の語尾で表しますが、英語では did を文の前のほうに置きます。

否定文

didn't は did not の短縮形です。改まった文章では did not を使います。

Yes/No で答える疑問文

短い答え：Yes, I did. No, he didn't. 「はい、しました」を Yes だけで終わらせず、did まで言うのが自然です。

疑問詞のある疑問文

疑問詞が最初、次に did、その次に主語が来ます。

was と were

be 動詞は did を使わず、自分で疑問文と否定文を作ります。

よくある間違い

• × Did you went? → Did you go?
• × I didn't saw it. → I didn't see it.
• × She didn't liked it. → She didn't like it.
• × Where you went? → Where did you go?
• × Did you were there? → Were you there?