单选题 Although buses in this district are scheduled to depart at a certain hour, they are often late.

【正确答案】 A
【答案解析】画线词scheduled的意思是：预定，排定(时间表)，可以替换它的词是选项A．planned。辨义：B．requested要求；C．obligated使……承担义务；D．10aded给……以负担，加载。故A为正确答案。