뭐해?mwo-hae? -Literally means what do? (In polite form, used with friends, people younger than you, or people close to you) 뭐하세요?/뭐해요?mwo-haseyo/mwo-haeyo?(In formal form, used with people older than you) or 뭐하고있어?/뭐하고있어요?mwo-hago-isseo?/mwo-hago-isseoyo? People use this as well. The way to know if it is formal or not, is it will either end in, 요yo, or 니다/니까 nida/nikka.

"What are you doing?" 1) 뭐하세요(mwo ha se yo - /mwʌ ha sʰe yo/)?(informal and polite) 2) 뭐해(mwo hae - /mwʌ hɛ/)?(informal and impolite) ^_______^