heavy schoolbags have long been a serious problem for them这句

heavy schoolbags have long been a serious problem for them这句 Big schoolbags have been a big problem for students for a lo 英语翻译Big school have been a serious problem for students for Big schoolbags＿ a large problem for student‘s for a long tim many of them have been with us for a long time翻译 I have been thinking about to purchase it for a long time.这句 l have been looking for someone for a long time how long have you__ fpr them?A been waited B waiting C been How long have you been to ShangHai?For a year. How long have you been looking for a job? Have you been here for a long time? I have been chasing for a long time