To change a adjective type sentence to a question, just add か (ka) at the end.
It’s new. あたらしい です (Atarashii desu).
Is it new? あたらしい です か? (Atarashii desu ka?)
For casual language, だ (da) replaces です (desu):
あたらしい だ Atarashii da.
But to change it to a question, you don’t change it to da ka. Instead, ka replaces da.
あたらしい か? (Atarashii ka?)
Women more often drop the ka:
あたらしい? (Atarashii?)
since apparently the ka sounds abrupt when speaking casually.
We can use more than one adjective to describe something, such as a big and tasty or interesting and fun.
To do this, we need to change the first adjective to its ‘-te’ form. Drop the final い (i) and replace it with くて (kute). We only need to change the first adjective.
Interesting and fun おもしろくて たのしい (omoshirokute tanoshii)
Cold and bad さむくて わるい (samukute warui)
New and beautiful あたらしくて きれい (atarashikute kirei)
Reference: The Complete Japanese Adjective Guide (Ann Tarumoto)
