Biti and htjeti: long, short, negative forms, and budem

• Short form (sam, si…): the normal case, in 2nd position: Umoran sam. — I'm tired.
• Long form (jesam…): in questions with li, in short answers, for emphasis: Jesi li umoran? — Jesam. — Are you tired? — Yes, I am.
• Negative (nisam…): one word, never “ne sam”. Nisam umoran.
• Budem: “be” with a future or wished-for meaning, after da, ako, kad, and in futur II: Želim da budeš sretan. — I want you to be happy. Imperative: Budi dobar! — Be good!

Htjeti works the same way: hoću, hoćeš, hoće… (long form: “I want”, questions, answers), ću, ćeš, će… (short form: future auxiliary), neću, nećeš… (negative). Hoćeš li kafu? — Hoću. — Do you want a coffee? — Yes. Neću doći. — I won't come.

Future of biti: bit ću / biću; past: bio sam, bila sam.