Verbseoul.
하다 verb (adj)
급격하다geupgyeokhadato be sudden

To say to be sudden politely in the present tense, use 급격해요 (geup-gyuh-kae-yoh). Below is the full conjugation of 급격하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
급격해
geup-gyuh-kae
급격해요
geup-gyuh-kae-yoh
급격합니다
geup-gyuh-kahm-nee-dah
Past
급격했어
geup-gyuh-kae-ssuh
급격했어요
geup-gyuh-kae-ssuh-yoh
급격했습니다
geup-gyuh-kae-sseum-nee-dah
Future
급격할 거야
geup-gyuh-kahl- -guh-yah
급격할 거예요
geup-gyuh-kahl- -guh-yae-yoh
급격할 겁니다
geup-gyuh-kahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
급격하세요
geup-gyuh-kah-sae-yoh
Suggestion / Let's Polite (요)
급격해요
geup-gyuh-kae-yoh
Question Polite (요)
급격해요?
geup-gyuh-kae-yoh-?
Connective “and” — (고)
급격하고
geup-gyuh-kah-goh
Conditional “if” — (면)
급격하면
geup-gyuh-kah-myuhn
Noun form — (기)
급격함
geup-gyuh-kahm