In a manner that makes a clear statement or declaration; in the style of a declarative sentence.
Declarative + -ly adverbial suffix. The -ly suffix transforms adjectives into adverbs, indicating manner or method of action.
Adding -ly to adjectives is one of English's most productive word-formation patterns—you can do it to almost any adjective and native speakers will understand you instantly. This is why English feels so flexible compared to languages with stricter grammar rules.
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