Verbseoul.
하다 verb
서약하다seoyakhadato vow

To say to vow politely in the present tense, use 서약해요 (suh-yah-kae-yoh). Below is the full conjugation of 서약하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
서약해
suh-yah-kae
서약해요
suh-yah-kae-yoh
서약합니다
suh-yah-kahm-nee-dah
Past
서약했어
suh-yah-kae-ssuh
서약했어요
suh-yah-kae-ssuh-yoh
서약했습니다
suh-yah-kae-sseum-nee-dah
Future
서약할 거야
suh-yah-kahl- -guh-yah
서약할 거예요
suh-yah-kahl- -guh-yae-yoh
서약할 겁니다
suh-yah-kahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
서약하세요
suh-yah-kah-sae-yoh
Suggestion / Let's Polite (요)
서약해요
suh-yah-kae-yoh
Question Polite (요)
서약해요?
suh-yah-kae-yoh-?
Connective “and” — (고)
서약하고
suh-yah-kah-goh
Conditional “if” — (면)
서약하면
suh-yah-kah-myuhn
Noun form — (기)
서약함
suh-yah-kahm