Verbseoul.
하다 verb (adj)
중대하다jungdaehadasignificant

To say significant politely in the present tense, use 중대해요 (choong-dae-hae-yoh). Below is the full conjugation of 중대하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
중대해
choong-dae-hae
중대해요
choong-dae-hae-yoh
중대합니다
choong-dae-hahm-nee-dah
Past
중대했어
choong-dae-hae-ssuh
중대했어요
choong-dae-hae-ssuh-yoh
중대했습니다
choong-dae-hae-sseum-nee-dah
Future
중대할 거야
choong-dae-hahl- -guh-yah
중대할 거예요
choong-dae-hahl- -guh-yae-yoh
중대할 겁니다
choong-dae-hahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
중대하세요
choong-dae-hah-sae-yoh
Suggestion / Let's Polite (요)
중대해요
choong-dae-hae-yoh
Question Polite (요)
중대해요?
choong-dae-hae-yoh-?
Connective “and” — (고)
중대하고
choong-dae-hah-goh
Conditional “if” — (면)
중대하면
choong-dae-hah-myuhn
Noun form — (기)
중대함
choong-dae-hahm