Verbseoul.
하다 verb
급감하다geupgamhadato drop/decrease rapidly

To say to drop/decrease rapidly politely in the present tense, use 급감해요 (geup-gahm-hae-yoh). Below is the full conjugation of 급감하다 across the three tenses and three everyday speech levels.

Conjugation table

TenseCasual (반말)Polite (요)Formal (합니다)
Present
급감해
geup-gahm-hae
급감해요
geup-gahm-hae-yoh
급감합니다
geup-gahm-hahm-nee-dah
Past
급감했어
geup-gahm-hae-ssuh
급감했어요
geup-gahm-hae-ssuh-yoh
급감했습니다
geup-gahm-hae-sseum-nee-dah
Future
급감할 거야
geup-gahm-hahl- -guh-yah
급감할 거예요
geup-gahm-hahl- -guh-yae-yoh
급감할 겁니다
geup-gahm-hahl- -guhm-nee-dah

Other useful forms

Command Polite (세요)
급감하세요
geup-gahm-hah-sae-yoh
Suggestion / Let's Polite (요)
급감해요
geup-gahm-hae-yoh
Question Polite (요)
급감해요?
geup-gahm-hae-yoh-?
Connective “and” — (고)
급감하고
geup-gahm-hah-goh
Conditional “if” — (면)
급감하면
geup-gahm-hah-myuhn
Noun form — (기)
급감함
geup-gahm-hahm