Black Friday: lifetime access is on a special offer in the app, until November 30. Black Friday: special offer on lifetime access, until November 30. Download
접촉전염은 감염병의 주요 전파 경로 중 하나입니다.jeobchokjeonyeomeun gamyeombyeong-ui juyo jeonpa gyeongno jung hanabnida.Contact transmission is one of the main routes of infection for infectious diseases.