Japanese

Making a past tense adjectival sentence in the plain form varies by whether the adjective is an い-adjective or a な-adjective.

For い-adjectives the final です is simply dropped after the -かった ending.

English	Japanese
The meal was unpalatable.	食しょく事じ　は　まずかった。 syokuzi ha mazukatta.
Your answer was not correct.	あなた　の　答こたえ　は　正ただしく　なかった。 anata no kotae ha tadasiku nakatta.

For な-adjectives, the adjective is followed by the plain past form of the copula, だった. And for the negative form, we drop the polite です after じゃ　なかった.

English	Japanese
Mary liked it very much.	メアリー　さん　は　とても　好すき　だった。 mearii san ha totemo suki datta.
The library was not quiet.	図と書しょ館かん　は　静しずか　じゃ　なかった。 tosyokan ha sizuka zya nakatta.