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A2 verb #2,000 よく出る 8分で読める

réagir

At the A1 level, 'réagir' is a word you might encounter when talking about basic feelings or physical responses. It is important to know that it means 'to react'. You might use it in simple sentences like 'Je réagis' (I react). At this stage, focus on the present tense and the basic idea of responding to something simple, like a loud noise or a funny joke. You don't need to worry about complex prepositions yet, just understand that when something happens, you 'réagis'. It is a regular -ir verb, so it's a good chance to practice your second-group conjugations. Think of it as the opposite of doing nothing. If someone says 'Hello', you react by saying 'Hello' back. Even though 'répondre' is more specific, 'réagir' covers the whole behavior. It's a foundational verb for describing human behavior in its simplest form.
At the A2 level, you should start using 'réagir' with the preposition 'à'. For example, 'réagir à un message' or 'réagir au froid'. You are expected to conjugate it correctly in the present tense, including the plural forms (nous réagissons). You should also be able to use it in the passé composé ('il a réagi') to describe things that happened. At this level, you can use adverbs to describe the reaction, such as 'bien' or 'mal'. 'Il a mal réagi' means he took it badly. This level is about expanding the context—moving from simple physical responses to social responses. You might talk about how a character in a story reacts to a problem. It's a key verb for the A2 'description of events' requirement. You should also recognize the noun 'une réaction'.
At the B1 level, you use 'réagir' to express opinions and describe more complex social situations. You can discuss how people react to social issues, news, or changes in the workplace. You should be comfortable using the verb in various tenses, including the future and the conditional ('je réagirais'). You will also start to see 'réagir' in more abstract contexts, like how a market reacts to news or how a system reacts to a change. At B1, you should be able to distinguish between 'réagir' and similar verbs like 'intervenir' or 'répondre'. You might use phrases like 'réagir au quart de tour' (to react instantly). Your ability to describe the *manner* of the reaction should be more nuanced, using a wider range of adverbs and prepositional phrases.
At the B2 level, 'réagir' is used in formal debates and analytical writing. You might analyze how a government reacts to a crisis or how a literary character's reactions reveal their personality. You should understand the nuances of reacting 'contre' (against) versus 'à' (to). The use of the subjunctive with 'réagir' becomes important, especially in complex sentences like 'Il est surprenant qu'il réagisse ainsi'. You should also be familiar with the chemical and biological uses of the verb in technical texts. At this level, you are expected to use 'réagir' to describe systemic responses, not just individual ones. You can discuss 'réactions en chaîne' (chain reactions) and other idiomatic or technical expressions. Your vocabulary should include synonyms like 'riposter' or 'rétorquer' for specific types of reactions.
At the C1 level, you explore the philosophical and psychological depths of 'réagir'. You can discuss the ethics of reaction versus action. You should be able to use the verb in highly formal or literary contexts. You might encounter 'réagir' in academic papers discussing 'réactivité' (reactivity) or in political science when discussing 'réactionnisme' (reactionary politics). Your use of the verb will be precise, often paired with sophisticated adverbs like 'viscéralement' (viscerally) or 'flegmatiquement' (phlegmatically). You can handle complex sentence structures where 'réagir' is part of a subordinate clause or a gerund phrase. You understand the subtle difference between a 'réaction' and a 'réponse' in high-level discourse, where 'réaction' might imply something less considered or more instinctive.
At the C2 level, you have a complete mastery of 'réagir' and all its connotations. You can use it to discuss complex scientific phenomena, deep psychological theories, or intricate political strategies. You understand its historical roots and how its usage has evolved. You can appreciate and use the verb in wordplay, irony, or highly metaphorical language. Whether you are reading 18th-century literature or modern scientific journals, you understand every nuance of 'réagir'. You can discuss the 'réaction' as a historical movement (like the Thermidorian Reaction) or as a biological imperative. Your ability to use the verb is indistinguishable from that of a highly educated native speaker, including the use of rare tenses like the passé simple ('il réagit') or the subjonctif imparfait, should the context require such a high register.
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réagir 30秒で

  • Réagir means 'to react' or 'to respond' to a stimulus.
  • It is a regular -ir verb (2nd group) like 'finir'.
  • It often takes the preposition 'à' (e.g., réagir à quelque chose).
  • Common in daily life, science, news, and social media contexts.

The French verb réagir is a second-group verb (-ir) that fundamentally describes the act of responding to a stimulus, whether physical, emotional, or chemical. At its core, it signifies an action taken in response to an external influence. In a linguistic sense, it is the counterpart to 'agir' (to act), where the prefix 'ré-' indicates a return or a response. To understand réagir, one must envision a chain of events: a trigger occurs, and a subsequent behavior follows. This can range from a simple biological reflex to a complex political maneuver. In everyday French, it is most commonly used to describe how people respond to news, behavior, or environmental changes.

Physical Reaction
The body's involuntary response to heat, cold, or pain.
Emotional Reaction
The psychological response to joy, sadness, or anger.
Chemical Reaction
The transformation of substances when brought into contact.

Il est important de réagir vite en cas d'urgence.

— Common safety advice

When we talk about 'réagir', we are often discussing the speed or the nature of the response. Is it a 'réaction vive' (sharp reaction) or a 'réaction tardive' (late reaction)? The verb captures the essence of interaction. In a social context, 'réagir' implies that someone has noticed something and has decided (or was forced by instinct) to show a change in state. It is a vital verb for expressing agency and consequence in the French language. For example, if someone insults you, how do you réagir? Do you stay calm or do you get angry? This verb is the bridge between the external world and the internal self.

Le marché a mal réagi aux nouvelles économiques.

Social Context
How a community or group responds to a new law or event.

Comment vas-tu réagir s'il ne vient pas ?

Furthermore, 'réagir' can be used in scientific contexts. A scientist might observe how two acids réagissent together. This versatility makes it an essential word for students reaching the A2 level and beyond. It moves the learner from simple descriptions of state to descriptions of dynamic interaction. Whether you are discussing a movie, a scientific experiment, or a personal conflict, 'réagir' provides the necessary linguistic tool to describe the 'back-and-forth' of life. It is not just about doing something; it is about doing something *because* of something else.

Elle n'a pas réagi à mes provocations.

Automaticity
The concept of 'réagir par réflexe' (reacting by reflex).

Les plantes réagissent à la lumière du soleil.

Using réagir correctly requires understanding its transitivity and its conjugation. As an intransitive verb, it often stands alone or is followed by the preposition à. For instance, 'réagir à une situation' (to react to a situation). It is a regular -ir verb of the second group, which means it follows the pattern of 'finir', 'choisir', and 'réussir'. This is crucial for learners to master, especially the plural forms in the present tense: nous réagissons, vous réagissez, ils réagissent. The 'iss' sound is a hallmark of this group and must be pronounced clearly.

Vous réagissez toujours avec beaucoup de calme.

In terms of tense usage, the passé composé is frequently used to describe a specific reaction that occurred in the past. It uses the auxiliary verb 'avoir' and the past participle 'réagi'. For example, 'J'ai réagi' (I reacted). When describing a habitual reaction or a state of reacting over time, the imparfait is appropriate: 'Je réagissais mal au stress' (I used to react poorly to stress). The imperative form is also common in urgent situations: 'Réagis !' (React! / Do something!).

Preposition 'À'
Always use 'à' before the object of the reaction: réagir à un stimulus.
Preposition 'Contre'
Use 'contre' when reacting against something: réagir contre une injustice.

One must also consider the adverbial accompaniment. How does one react? 'Vivement' (strongly), 'froidement' (coldly), 'immédiatement' (immediately), or 'avec enthousiasme' (with enthusiasm). These adverbs provide the nuance necessary for sophisticated communication. In professional settings, you might hear 'réagir en temps réel' (to react in real-time), which is a common phrase in tech and business. In medical contexts, a patient might 'réagir au traitement' (react/respond to treatment). Understanding these pairings helps in moving from basic sentences to natural-sounding French.

Il faut réagir avant qu'il ne soit trop tard.

You will encounter réagir in a wide variety of environments, from the living room to the laboratory. In news broadcasts, journalists often ask, 'Comment a réagi le Premier ministre ?' (How did the Prime Minister react?). This is a standard way to seek a comment or a response to a political event. In the world of sports, commentators might say, 'L'équipe a bien réagi après le premier but' (The team reacted well after the first goal), indicating a comeback or a change in momentum.

Les marchés financiers ont réagi négativement à l'annonce.

In daily life, parents might use it when talking about their children: 'Il réagit très mal quand il est fatigué' (He reacts very badly when he is tired). In a medical or scientific setting, it is the go-to verb for describing interactions. A doctor might ask, 'Comment votre corps a-t-il réagi au nouveau médicament ?' (How did your body react to the new medicine?). In social media contexts, 'réagir' is the term used for 'reacting' to a post (likes, hearts, etc.), though 'liker' is also used informally.

TV News
Used to describe political or social responses to events.
Science Class
Used for chemical reactions and biological stimuli.
Daily Conversation
Used for emotional responses and personal interactions.

On attend de voir comment le public va réagir.

One of the most frequent errors for English speakers is the conjugation of réagir. Because it is a second-group verb, many learners forget the -iss- in the plural forms. They might say 'nous réageons' instead of the correct nous réagissons. This is a classic mistake that marks a learner as a beginner. Another common error is the choice of preposition. While in English we 'react to' something, in French we also use 'à', but learners often forget to contract the article (e.g., 'réagir au' instead of 'réagir à le').

Incorrect: Nous réageons à la nouvelle.
Correct: Nous réagissons à la nouvelle.

Another pitfall is confusing 'réagir' with 'répondre'. If you are answering a question, use 'répondre'. If you are showing a physical or emotional response to a situation, use 'réagir'. For example, 'Il a répondu à ma question' (He answered my question) vs 'Il a réagi avec colère' (He reacted with anger). Furthermore, some learners try to use 'réagir' as a transitive verb without a preposition, which is incorrect. You cannot 'réagir une situation'; you must 'réagir à une situation'.

The 'iss' sound
Forgetting to add 'iss' in nous/vous/ils forms.
Preposition Omission
Forgetting the 'à' after the verb.

Several words in French share a semantic field with réagir, but each has its own nuance. Répondre is the most common synonym, but it specifically implies a verbal or written response. Agir is the root verb, meaning simply 'to act' or 'to take action', without the necessity of it being a response. Interagir (to interact) is used when two or more entities are reacting to each other simultaneously, often used in social or scientific contexts.

Il est temps d'agir au lieu de simplement réagir.

Other related terms include riposter, which carries a more aggressive or defensive tone, like 'to strike back' or 'to retort'. Contrer means to counter an action. In a more passive sense, subir (to undergo/suffer) is the opposite of reacting actively; it is when the action happens to you and you don't or can't fight back. Understanding these distinctions allows a learner to choose the precise word for the situation.

Riposter
To react quickly and often sharply, especially in an argument.
Rétorquer
To react verbally with a clever or sharp answer.

How Formal Is It?

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知っておくべき文法

レベル別の例文

1

Je réagis quand tu parles.

I react when you speak.

Present tense, 1st person singular.

2

Tu réagis vite.

You react fast.

Present tense, 2nd person singular.

3

Il réagit au bruit.

He reacts to the noise.

Verb + à + noun.

4

Elle réagit avec un sourire.

She reacts with a smile.

Verb + avec + noun.

5

Nous réagissons ensemble.

We react together.

Present tense, 1st person plural (-iss-).

6

Vous réagissez bien.

You (plural) react well.

Present tense, 2nd person plural (-iss-).

7

Ils réagissent au froid.

They react to the cold.

Present tense, 3rd person plural (-iss-).

8

Ça réagit maintenant.

It is reacting now.

3rd person singular 'ça'.

1

J'ai réagi trop tard.

I reacted too late.

Passé composé with 'avoir'.

2

Elle a réagi à mon email.

She reacted to my email.

Passé composé + à.

3

Nous avons réagi calmement.

We reacted calmly.

Passé composé + adverb.

4

Pourquoi n'as-tu pas réagi ?

Why didn't you react?

Negative question in passé composé.

5

Il réagit toujours de la même façon.

He always reacts the same way.

Present tense for habit.

6

Les enfants réagissent au sucre.

Children react to sugar.

Plural subject + à + noun.

7

Vous devez réagir maintenant.

You must react now.

Devoir + infinitive.

8

Elle ne réagit pas à la douleur.

She doesn't react to pain.

Negation + à.

1

Si tu m'aides, je réagirai mieux.

If you help me, I will react better.

Future tense.

2

Il réagirait s'il savait la vérité.

He would react if he knew the truth.

Conditional tense.

3

Le public a réagi avec enthousiasme.

The audience reacted with enthusiasm.

Passé composé + prepositional phrase.

4

Comment réagiriez-vous dans cette situation ?

How would you react in this situation?

Conditional question.

5

Elle réagissait souvent par la colère.

She often reacted with anger.

Imparfait for past habit.

6

Il est important de réagir contre l'injustice.

It is important to react against injustice.

Infinitive + contre.

7

Les marchés réagissent aux rumeurs.

Markets react to rumors.

Present tense, plural.

8

Nous réagissons selon les circonstances.

We react according to the circumstances.

Present tense + selon.

1

Il faut que le gouvernement réagisse.

The government must react.

Subjunctive mood.

2

Bien qu'il soit surpris, il n'a pas réagi.

Although he was surprised, he didn't react.

Concession clause + passé composé.

3

Le produit chimique réagit violemment à l'eau.

The chemical reacts violently to water.

Scientific context.

4

Elle a réagi au quart de tour.

She reacted instantly.

Idiomatic expression.

5

Ils ont réagi en ignorant la provocation.

They reacted by ignoring the provocation.

Gerund (en + participe présent).

6

On ne peut pas prévoir comment elle va réagir.

One cannot predict how she will react.

Futur proche in a subordinate clause.

7

Le corps réagit pour se protéger.

The body reacts to protect itself.

Infinitive of purpose.

8

Sa façon de réagir est exemplaire.

His way of reacting is exemplary.

Infinitive used as a noun.

1

Il est impératif que nous réagissions de manière coordonnée.

It is imperative that we react in a coordinated manner.

Subjunctive plural.

2

L'organisme réagit viscéralement à cette agression.

The organism reacts viscerally to this aggression.

High-level adverb 'viscéralement'.

3

Face à l'adversité, il a su réagir avec dignité.

Faced with adversity, he knew how to react with dignity.

Complex prepositional phrase.

4

La bourse réagit par une volatilité accrue.

The stock market reacts with increased volatility.

Technical financial terminology.

5

Elle réagit à l'encontre de toute logique.

She reacts against all logic.

Formal phrase 'à l'encontre de'.

6

Il a réagi en connaissance de cause.

He reacted with full knowledge of the facts.

Idiomatic formal phrase.

7

Comment réagir sans paraître agressif ?

How to react without appearing aggressive?

Infinitive question.

8

Sa capacité à réagir promptement est un atout.

His ability to react promptly is an asset.

Noun phrase + infinitive.

1

L'histoire nous enseigne que les peuples finissent par réagir.

History teaches us that peoples eventually react.

General philosophical statement.

2

Il réagit comme s'il eût été piqué par un vif argent.

He reacted as if he had been stung by quicksilver.

Literary past subjunctive.

3

La structure moléculaire réagit aux photons incidents.

The molecular structure reacts to incident photons.

Highly technical scientific usage.

4

Réagir, c'est exister dans le regard de l'autre.

To react is to exist in the gaze of the other.

Philosophical aphorism.

5

Elle ne put s'empêcher de réagir par un ricanement sardonique.

She could not help but react with a sardonic sneer.

Passé simple + literary vocabulary.

6

Le système immunitaire réagit en cascade.

The immune system reacts in a cascade.

Technical medical metaphor.

7

Il réagit à la moindre sollicitation intellectuelle.

He reacts to the slightest intellectual solicitation.

Abstract formal usage.

8

Qu'il réagisse ou non, le sort en est jeté.

Whether he reacts or not, the die is cast.

Subjunctive of indifference.

よく使う組み合わせ

réagir vivement
réagir mal
réagir bien
réagir immédiatement
réagir à temps
réagir avec calme
réagir par réflexe
réagir contre une loi
réagir au quart de tour
réagir en chaîne

よく使うフレーズ

Comment as-tu réagi ?

Il faut réagir.

Ne pas réagir.

Réagir à chaud.

Réagir avec retard.

Réagir positivement.

Réagir négativement.

Réagir en silence.

Réagir de façon appropriée.

Réagir face à l'urgence.

よく混同される語

réagir vs répondre

réagir vs agir

réagir vs ressentir

慣用句と表現

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間違えやすい

réagir vs répondre

To answer verbally or in writing.

réagir vs agir

To act, not necessarily as a response.

réagir vs ressentir

To feel internally, whereas réagir is external.

文型パターン

使い方

nuance

'Réagir' is more about the act, 'répondre' is more about the content.

prepositions

Use 'à' for targets, 'contre' for opposition.

よくある間違い
  • Saying 'nous réageons' instead of 'nous réagissons'.
  • Forgetting the preposition 'à' after the verb.
  • Using 'réagir' when 'répondre' (answering a question) is more appropriate.
  • Using 'être' as the auxiliary in the passé composé.
  • Confusing 'réagir' with 'regretter'.

ヒント

Plural Forms

Always remember the 'iss' in nous, vous, and ils forms. It's 'nous réagissons', not 'nous réageons'.

Prepositions

Always pair 'réagir' with 'à' when you are reacting to something specific.

Adverbs

Use adverbs like 'vite', 'bien', or 'mal' to make your sentences more descriptive.

Subjunctive

After 'il faut que', use the subjunctive form 'réagisse'.

Context

If you hear 'réaction', the verb 'réagir' is likely nearby.

Protests

In news about France, 'réagir' often refers to public demonstrations.

Reaction

The English word 'reaction' is your best friend for remembering this verb.

Variety

Try using 'riposter' if the reaction is an attack or a sharp reply.

Reflexes

Use 'réagir' for physical reflexes like blinking or jumping.

Conjugation

Review 'finir' conjugation to master 'réagir' instantly.

暗記しよう

語源

From Latin 're-' (again/back) + 'agere' (to do/act).

文化的な背景

Reacting is often public and vocal in France.

Quick reactions are valued in the fast-paced Parisian business world.

実生活で練習する

実際の使用場面

会話のきっかけ

"Comment aurais-tu réagi à ma place ?"

"Comment les gens réagissent-ils à cette nouvelle ?"

"Est-ce que tu réagis souvent par impulsion ?"

"Comment réagir face à un client difficile ?"

"As-tu déjà réagi de façon excessive ?"

日記のテーマ

Décrivez une situation où vous avez bien réagi.

Comment réagissez-vous face au stress ?

Pourquoi est-il parfois difficile de réagir ?

Une réaction chimique qui vous fascine.

Réagir ou ignorer : quelle est la meilleure stratégie ?

よくある質問

10 問

Yes, it is a regular verb of the second group, conjugated like 'finir'.

It uses 'avoir'. Example: 'J'ai réagi'.

The noun form is 'une réaction'.

No, you must say 'réagir à une situation'.

It means to react instantly or very quickly.

Yes, it is used for chemical and biological reactions.

You can say 'surréagir' or 'réagir de manière excessive'.

The present participle is 'réagissant'.

No, it is intransitive and usually takes an indirect object with 'à'.

Yes, it is a very common verb used in many contexts.

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