Many chemicals and artificial ingredients which it is sometimes difficult to know exactly what is inside them. 근데 which가 아닌겅 알겠는데 that이 들어가는게 답이던데 That절이 되려면 앞에 선행사가 없어야하지않음.?.?. 아 모루겟다ㅠ
영어문법 왜틀렷는지좀 ㅈㅂ 알려워오