Teach Us, Teacher
Past form of adjectives (Lesson 19)You've learned there are two kinds of adjectives in Japanese, I-adjectives and NA-adjectives. I-adjectives end with the syllable I, such as YASUI "inexpensive." NA-adjectives take NA after them, when they modify nouns, such as in SUKI, "to like." When it modifies a noun, it becomes SUKINA. So, somebody's “favourite manga” is SUKINA MANGA. To get the past form of I-adjectives, you change I to KATTA. For example, the past form of YASUI (inexpensive) is YASUKATTA. The past form of TAKAI (expensive) is TAKAKATTA. YOKATTA (I’m glad or It was good), in this lesson, is the only exception. The adjective for "good" in the present tense, II, becomes YOKATTA in the past tense. This is an irregular conjugation, so you will just have to memorize it.
To turn I-adjectives into the past negative, you change I to KU NAKATTA. YASUI (inexpensive) for example, becomes YASUKU NAKATTA (was not inexpensive). II (good) becomes YOKU NAKATTA.
To get the past form of NA-adjectives, you add DATTA at the end of the adjectives. So, SUKI (to like, be fond of) becomes SUKI DATTA (liked, was(were) fond of). BENRI (convenient) becomes BENRI DATTA (was convenient).
To turn NA-adjectives into the past negative, you add DEWA NAKATTA. SUKI (to like) becomes SUKI DEWA NAKATTA (didn’t like).