Verbseoul.
하다 verb
확신하다hwaksinhadato be convinced, to be sure, to be certain

To say to be convinced, to be sure, to be certain politely in the present tense, use 확신해요 (hwahg-sheen-hae-yoh). Below is the full conjugation of 확신하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
확신해
hwahg-sheen-hae
확신해요
hwahg-sheen-hae-yoh
확신합니다
hwahg-sheen-hahm-nee-dah
Past
확신했어
hwahg-sheen-hae-ssuh
확신했어요
hwahg-sheen-hae-ssuh-yoh
확신했습니다
hwahg-sheen-hae-sseum-nee-dah
Future
확신할 거야
hwahg-sheen-hahl- -guh-yah
확신할 거예요
hwahg-sheen-hahl- -guh-yae-yoh
확신할 겁니다
hwahg-sheen-hahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
확신하세요
hwahg-sheen-hah-sae-yoh
Suggestion / Let's Polite (요)
확신해요
hwahg-sheen-hae-yoh
Question Polite (요)
확신해요?
hwahg-sheen-hae-yoh-?
Connective “and” — (고)
확신하고
hwahg-sheen-hah-goh
Conditional “if” — (면)
확신하면
hwahg-sheen-hah-myuhn
Noun form — (기)
확신함
hwahg-sheen-hahm