During King Gyeonsun's rule, the Hyrngsan Hyeongsan River could not flow to the sea because of Mount Hyeongje. so So it flooded after heavy rains.
→ Hyeongsan 철자 수정, 문장 시작은 대문자 So로 써요.
The king ordered his people to dig a sluice though through the mountain.
→ though → through (통과하다 뜻)
He wanted make to make a safe city.
→ want 뒤에는 to + 동사 형태를 써요.
He promised dragon to become a dragon after he died and crush crush the mountain.
→ promised 뒤에는 to + 동사, 의미가 자연스럽게 이어지도록 고쳐요.
Upon he death Upon his death, the king became a giant serpent.
→ he → his (소유격)
Yugeumi Plain after the young boy, Yugeumi Plain was named after the young boy, and the two mountains beccame became Mount Hyeong and Mount je Je.
→ 문장이 빠져 있어서 was named 추가, became 철자 수정, 고유명사는 대문자!
Score: B+
Tips)
문장이 길어져서 조금 어려웠지만 잘 썼어요 👍