Reagoivatko

Reagoivatko is a Finnish grammatical form used to form yes-no questions in the present tense with a third-person plural subject of the verb reagoida, which means to react or respond. The verb reagoida belongs to the class of Finnish imperfective verbs, and in ordinary statements it appears as reagoivat (they react). When turning the statement into a question, the question suffix -ko/-kö is added to the verb form, yielding reagoivatko.

In use, the question particle -ko/-kö attaches to the element carrying the main action, often the finite verb, and the word order typically places the verb with its suffix at the beginning of the sentence followed by the subject. Examples: Reagoivatko he? (Do they react?), Reagoivatko eläimet tähän signaaliin? (Do the animals react to this signal?). Finnish allows alternative word orders in questions, but the verb-first pattern with the -ko/-kö suffix remains standard for yes-no inquiries.

Formation and rules: -ko/-kö is a general Finnish question suffix that shows up in yes-no questions and harmonizes with the preceding vowel. In the form reagoivatko, it attaches to the plural present tense form reagoivat, creating a single contracted question word rather than a separate particle. The meaning is context-dependent and relies on tense and aspect conveyed by surrounding time expressions since Finnish uses context to mark past or present actions rather than distinct auxiliary forms.

Related forms include other verb stems combined with -ko/-kö to form different questions, such as kysyivätkö (did they ask?) or reagoisinko (should I react?).

Overall, reagoivatko exemplifies Finnish question formation through the -ko/-kö suffix applied to the appropriate verb form, here indicating a yes-no question about multiple actors.