More na-adjectives

Most na-adjectives at this level are two-kanji words from Chinese, and many of them double as nouns: 必要(ひつよう), 重要(じゅうよう), 特別(とくべつ). A smaller group of native words ends in か or やか — 豊(ゆた)か, 穏(おだ)やか, 鮮(あざ)やか — and describes a quality that is felt rather than measured. Add に and any of them becomes an adverb: 正確(せいかく)に, 勝手(かって)に, 急(きゅう)に.