Verbseoul.
하다 verb (adj)
무익하다muikhadato be futile, to be useless

To say to be futile, to be useless politely in the present tense, use 무익해요 (moo-ee-kae-yoh). Below is the full conjugation of 무익하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
무익해
moo-ee-kae
무익해요
moo-ee-kae-yoh
무익합니다
moo-ee-kahm-nee-dah
Past
무익했어
moo-ee-kae-ssuh
무익했어요
moo-ee-kae-ssuh-yoh
무익했습니다
moo-ee-kae-sseum-nee-dah
Future
무익할 거야
moo-ee-kahl- -guh-yah
무익할 거예요
moo-ee-kahl- -guh-yae-yoh
무익할 겁니다
moo-ee-kahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
무익하세요
moo-ee-kah-sae-yoh
Suggestion / Let's Polite (요)
무익해요
moo-ee-kae-yoh
Question Polite (요)
무익해요?
moo-ee-kae-yoh-?
Connective “and” — (고)
무익하고
moo-ee-kah-goh
Conditional “if” — (면)
무익하면
moo-ee-kah-myuhn
Noun form — (기)
무익함
moo-ee-kahm