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How to change adjectives to adverbs (Lesson 22)Japanese adjectives conjugate to become adverbs. We can change I adjectives that end with syllable I, such as HAYAI (early), to adverbs by changing the final I to KU. So, HAYAI becomes HAYAKU. If HAYAKU and NARIMASHITA (have become) are linked together, they become HAYAKU NARIMASHITA (have become early).
As for NA adjectives, I'll explain with an adjective, JÔZU (to be good at) as an example.
You've learned that when a NA adjective modifies a noun, it takes NA at its end. So, JÔZU becomes JÔZUNA. We can change NA adjectives to adverbs by adding NI after the words. So, JÔZU becomes JÔZUNI. "I have become good at" is JÔZUNI NARIMASHITA.