Verbseoul.
하다 verb (adj)
딱딱하다ttakttakhadato be hard, firm (resistant to pressure)

To say to be hard, firm (resistant to pressure) politely in the present tense, use 딱딱해요 (ttahg-ttah-kae-yoh). Below is the full conjugation of 딱딱하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
딱딱해
ttahg-ttah-kae
딱딱해요
ttahg-ttah-kae-yoh
딱딱합니다
ttahg-ttah-kahm-nee-dah
Past
딱딱했어
ttahg-ttah-kae-ssuh
딱딱했어요
ttahg-ttah-kae-ssuh-yoh
딱딱했습니다
ttahg-ttah-kae-sseum-nee-dah
Future
딱딱할 거야
ttahg-ttah-kahl- -guh-yah
딱딱할 거예요
ttahg-ttah-kahl- -guh-yae-yoh
딱딱할 겁니다
ttahg-ttah-kahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
딱딱하세요
ttahg-ttah-kah-sae-yoh
Suggestion / Let's Polite (요)
딱딱해요
ttahg-ttah-kae-yoh
Question Polite (요)
딱딱해요?
ttahg-ttah-kae-yoh-?
Connective “and” — (고)
딱딱하고
ttahg-ttah-kah-goh
Conditional “if” — (면)
딱딱하면
ttahg-ttah-kah-myuhn
Noun form — (기)
딱딱함
ttahg-ttah-kahm