Na adjectives in the past

[Guregori]

Could you please clear up a doubt I have about adjectives in the past when put before a noun.

If I've understood correctly you can put an -i adjective in the past form before a noun, for example:

安くて明るかった部屋です。
It was a cheap and bright room.

I'm unsure about -na adjectives because online I can only find examples of -na adjectives as the predicate in the past, and not preceding a noun.
Would it be: adjective + na + noun + deshita ?

かれは親切な人でした。
He wasn't a kind person.

 

[BrianLewis]

It's treated the same as a noun.

この人は親切でした
昨日この掲示板はとても静かだった (さくじつこのけいじばんはとてもしずかだった)

Na adjectives are also called adjectival nouns, so that explains it.

 

[Toritoribe]

Could you please clear up a doubt I have about adjectives in the past when put before a noun.

If I've understood correctly you can put an -i adjective in the past form before a noun, for example:

安くて明るかった部屋です。
It was a cheap and bright room.

I'm unsure about -na adjectives because online I can only find examples of -na adjectives as the predicate in the past, and not preceding a noun.
Would it be: adjective + na + noun + deshita ?

かれは親切な人でした。
He wasn't a kind person.

"Stem of na-adjective + だった + noun" is what you are looking for.
e.g.
あんなに親切だった人が、最近冷たくなった。
lit. A person who was so kind has become cold-hearted recently.