基本の説明Overview
英語の文には「〜です／〜します」と言い切る肯定文のほかに、「〜ですか」とたずねる疑問文と、「〜ではありません」と打ち消す否定文があります。疑問文・否定文の作り方は、文の中心になる語が be動詞・一般動詞・助動詞（can, will など）のどれかで変わります。Besides affirmative sentences (“It is…”, “I do…”), English has questions (“Is it…?”) and negatives (“It is not…”). How you form them depends on the main verb: a be-verb, an ordinary verb, or a modal (can, will…).
be動詞と助動詞の文は、その語を動かすだけで作れます。疑問文ならその語を主語の前に出し、否定文ならその語のあとに not を置きます。一般動詞の文は、動詞そのものを動かせないので、do / does という助けの語を使います。主語が三人称単数（he, she, it, Tom など）のときは does、それ以外は do です。With a be-verb or a modal, you only have to move that word: bring it before the subject for a question, or put not after it for a negative. An ordinary verb cannot be moved like that, so English calls in a helper word, do / does. Use does for a third-person singular subject (he, she, it, Tom…) and do for all others.
| 動詞の種類Type of verb | 肯定文Affirmative | 疑問文Question | 否定文Negative |
|---|---|---|---|
| be動詞Be-verb | She is busy. | Is she busy? | She is not (isn't) busy. |
| 一般動詞（I・you・複数）Ordinary verb (I, you, plural) | You play tennis. | Do you play tennis? | You don't play tennis. |
| 一般動詞（三人称単数）Ordinary verb (3rd-person singular) | He plays tennis. | Does he play tennis? | He doesn't play tennis. |
| 助動詞（can など）Modal (can, etc.) | She can swim. | Can she swim? | She can't (cannot) swim. |
does を使う文では、動詞に三人称単数の s をつけません。三単現の s は does が引き受けているので、動詞は原形に戻ります（He plays → Does he play? / He doesn't play）。Do not add the third-person -s to the verb in a sentence with does. Does already carries the -s, so the verb goes back to its base form (He plays → Does he play? / He doesn't play).
疑問詞には what（何）、who（だれ）、where（どこ）、when（いつ）、why（なぜ）、how（どのように）などがあり、疑問詞のあとは「ふつうの疑問文の語順」を続けます（Where does Ken live?）。ただし、疑問詞そのものが主語になる場合（Who lives here?）は、do / does を使わず、ふつうの文の語順のままです。Question words include what, who, where, when, why and how. After the question word, continue with normal question word order (Where does Ken live?). However, when the question word itself is the subject (Who lives here?), no do / does is used and the word order stays like a statement.
例文で確認Example sentences
① be動詞の疑問文・否定文1. Be-verb questions and negatives
② 一般動詞の疑問文（Do / Does）2. Questions with ordinary verbs (Do / Does)
③ 一般動詞の否定文（don't / doesn't）3. Negatives with ordinary verbs (don't / doesn't)
④ 助動詞（can / will）の疑問文・否定文4. Questions and negatives with modals (can / will)
⑤ 疑問詞のある疑問文5. Questions with a question word
⑥ 疑問詞が主語になる疑問文6. Questions where the question word is the subject
確認クイズQuick check
空所に入る語を答えましょう（短縮形を使ってよい問題もあります）。Fill in each blank (short forms are fine where the answer needs a negative).
- ___ you like music?
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Do — 主語が you なので Do で始める。The subject is you, so start with Do. - ___ your sister play the piano?
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Does — your sister は she にあたる三人称単数なので Does。your sister is a she (third-person singular), so Does. - My father ___ drink tea. (negative sentence)
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doesn't — My father は三人称単数なので doesn't（does not）。あとの drink は原形のまま。My father is third-person singular, so doesn't (does not). The following drink stays in its base form. - This ___ my bag. (negative sentence)
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isn't — be動詞の否定文は、be動詞のあとに not。is not の短縮形は isn't。For a be-verb negative, put not after the be-verb. The short form of is not is isn't. - She ___ swim fast. (negative sentence)
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can't — 助動詞 can の否定文は can't（cannot）。don't / doesn't は使わない。The negative of the modal can is can't (cannot). Do not use don't / doesn't. - Where ___ Ken live?
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does — Ken は三人称単数なので does。疑問詞のあとは疑問文の語順。Ken is third-person singular, so does. After the question word, use question word order.
おさえておきたいポイントKey points
- 疑問文・否定文の作り方は、文の動詞が be動詞・一般動詞・助動詞のどれかで決まるHow to form questions and negatives depends on whether the verb is a be-verb, an ordinary verb or a modal
- be動詞・助動詞の文は、その語を主語の前に出せば疑問文、そのあとに not を置けば否定文With a be-verb or modal, moving it before the subject makes a question, and putting not after it makes a negative
- 一般動詞の文は do / does を使う。主語が三人称単数なら does、それ以外は doOrdinary-verb sentences use do / does: does for a third-person singular subject, do for the rest
- do / does / don't / doesn't のあとの動詞は必ず原形（三単現の s は does が引き受ける）After do / does / don't / doesn't the verb is always in its base form (does carries the third-person -s)
- 疑問詞のある疑問文は「疑問詞 + 疑問文の語順」。疑問詞が主語のときだけはふつうの文の語順A question with a question word is “question word + question order”; only when the question word is the subject, the order is like a statement
- 答えるときは、たずねられた語に合わせる（Do you…? → Yes, I do.／Is she…? → No, she isn't.）Answer with the same helper word that was used in the question (Do you…? → Yes, I do. / Is she…? → No, she isn't.)