How to say 'I want to be red' in Japanese?


`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.` ?




It all depends on the context (if you don't provide more, we cannot help
much), but in some cases you might use:  
- Be red! 赤くなれ！  
- It's being red at the moment 現在赤です。  
- Be polite! 丁寧に話せ！  
- He's being polite 今だけ丁寧に喋りやがっている

