Verbseoul.
하다 verb (adj)
강하다ganghadastrong, powerful

To say strong, powerful politely in the present tense, use 강해요 (gahng-hae-yoh). Below is the full conjugation of 강하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
강해
gahng-hae
강해요
gahng-hae-yoh
강합니다
gahng-hahm-nee-dah
Past
강했어
gahng-hae-ssuh
강했어요
gahng-hae-ssuh-yoh
강했습니다
gahng-hae-sseum-nee-dah
Future
강할 거야
gahng-hahl- -guh-yah
강할 거예요
gahng-hahl- -guh-yae-yoh
강할 겁니다
gahng-hahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
강하세요
gahng-hah-sae-yoh
Suggestion / Let's Polite (요)
강해요
gahng-hae-yoh
Question Polite (요)
강해요?
gahng-hae-yoh-?
Connective “and” — (고)
강하고
gahng-hah-goh
Conditional “if” — (면)
강하면
gahng-hah-myuhn
Noun form — (기)
강함
gahng-hahm