Verbseoul.
으 irregular (adj)
슬프다seulpeudato be sad

To say to be sad politely in the present tense, use 슬퍼요 (seul-puh-yoh). Below is the full conjugation of 슬프다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
슬퍼
seul-puh
슬퍼요
seul-puh-yoh
슬픕니다
seul-peum-nee-dah
Past
슬펐어
seul-puh-ssuh
슬펐어요
seul-puh-ssuh-yoh
슬펐습니다
seul-puh-sseum-nee-dah
Future
슬플 거야
seul-peul- -guh-yah
슬플 거예요
seul-peul- -guh-yae-yoh
슬플 겁니다
seul-peul- -guhm-nee-dah

Other useful forms

Command Polite (세요)
슬프세요
seul-peu-sae-yoh
Suggestion / Let's Polite (요)
슬퍼요
seul-puh-yoh
Question Polite (요)
슬퍼요?
seul-puh-yoh-?
Connective “and” — (고)
슬프고
seul-peu-goh
Conditional “if” — (면)
슬프면
seul-peu-myuhn
Noun form — (기)
슬픔
seul-peum