Question

9. John        to his boss why he was late for the important meeting the whole morning,but his boss just didn't listen to him. (explain) 

John花了一上午时间向他的老板解释为什么他在那个重要会议上迟到了，但是他的老板并不听。

Answer 1

9. had been explaining由the whole morning得知John—上午时间一直在向老板解释。表达过去一段时间一直在做某事,要用过去完成进行时。