Watasi wa akaku sitai.
?
Watasi wa akakaritai.
?
How to say 'Be red!'?
Akaku siro!
?
Akakare!
?
How to say 'It's being red at the moment (as in: it will turn purple and then blue soon)'?
Kore wa akaku site iru tadaima.
?
Kore wa akakarete iru tadaima.
?
For na-adjectives:
How to say 'Be polite!'
Teinei ni siro!
?
Teinei nare!
?
And how to say 'He's being polite (as in: he's usually not but in order to get what he wants, he's being polite at the moment).'?
Kare wa teinei ni site iru.
?
Kare wa teinei narete iru.
?