Modals

Can, can't, must, have to for ability and obligation

はじめに

法助動詞（モーダル動詞）は、能力・可能性・許可・義務を表す特別な助動詞です。主語によって形が変わらず、後ろには必ず動詞の原形が来ます。

日本語では「〜できる」「〜しなければならない」のように語尾で表しますが、英語ではcan、must、shouldなどの助動詞を動詞の前に置きます。基本レベルではまず「can（〜できる）」と「must（〜しなければならない）」が必須。

この2つを使いこなせると、単なる事実の叙述を超えて「何が可能か、何が許されるか、何が必要か」を表現できるようになります。ニュアンスの幅がぐっと広がりますよ。

テーマ

この章の英文法一覧（13）

• can / can't Expresses ability, possibility, or permission
• must / have to Expresses obligation or necessity
• could (past ability) Expresses past ability or past possibility
• may / might Expresses possibility or asks for permission
• will (future) Expresses future actions, promises, and spontaneous decisions
• going to (future) Expresses planned future actions and predictions based on evidence
• Let's (suggestions) Making suggestions that include yourself
• Shall (offers & suggestions) Offering to do something or making suggestions
• should / shouldn't (Basic Advice) Giving simple advice or opinions
• could (Polite Request) Making polite requests and asking for permission
• would like Polite way to express wants
• May I...? (Formal Permission) Asking for permission formally
• might (Weak Possibility) Expressing something is possible but uncertain