Verbseoul.
하다 verb (adj)
심하다simhadato be severe, to be extreme

To say to be severe, to be extreme politely in the present tense, use 심해요 (sheem-hae-yoh). Below is the full conjugation of 심하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
심해
sheem-hae
심해요
sheem-hae-yoh
심합니다
sheem-hahm-nee-dah
Past
심했어
sheem-hae-ssuh
심했어요
sheem-hae-ssuh-yoh
심했습니다
sheem-hae-sseum-nee-dah
Future
심할 거야
sheem-hahl- -guh-yah
심할 거예요
sheem-hahl- -guh-yae-yoh
심할 겁니다
sheem-hahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
심하세요
sheem-hah-sae-yoh
Suggestion / Let's Polite (요)
심해요
sheem-hae-yoh
Question Polite (요)
심해요?
sheem-hae-yoh-?
Connective “and” — (고)
심하고
sheem-hah-goh
Conditional “if” — (면)
심하면
sheem-hah-myuhn
Noun form — (기)
심함
sheem-hahm