The reason ________ he told the teacher ________ he was late was that he got up late．
A.why; thatB.that; whyC.which; thatD.that; which在线课程B
the reason后面有两个定语从句，其中第一个缺少tell的直接宾语，因此用关系代词which或that引导；第二个定语从句不缺少成分，且说明reason的内容，因此要用why引导。因此答案是B。