Professor Tang didn't give us a speech today.It was he had a traffic accident on the way

问题补充：

Professor Tang didn give us a speech today.It was he had a traffic accident on the way to school.

A. that

B. when

C. why

D. because

答案：

A. that

B. when

C. why

(答案→)D. because

解析：根据“那是因为他在去学校的路上出了交通事故”可知选D。