Is this the reason _________ at the meeting for his carelessness in his work?
A.he explainedB.what he explainedC.how he explainedD.why he explained在线课程A
解析：
the reason后可用关系代词that引导定语从句．也可用关系副词why引导定语从句.在该句中，因为引导定语从句的关系代词that作 explained的宾语，所以可以省略掉.这句意思是“这就是他在会议上对他为什么在工作上粗心大意的理由所作的解释吗?”最佳答案为A.