This is the 4868th most frequent French word.
réagisse
"Réagisse" is the subjunctive form of "réagir," meaning "to react."
The verb 'réagisse' is used in the subjunctive mood because it follows an expression of importance ('Il est important que'). This form indicates a level of uncertainty or situation dependency.
Il est important qu'elle réagisse rapidement à la situation.
It is important that she reacts quickly to the situation.
Here, 'réagisse' is in the subjunctive mood, triggered by the verb 'douter' which implies doubt or uncertainty regarding the reaction.
Je doute qu'il réagisse comme prévu.
I doubt he reacts as planned.
In this case, 'réagissent' is in the indicative mood because it refers to a factual statement about their reaction—its form depends on the specific subject 'ils'.