The reason he was late for school was he had to send his mother to a hospital.A. that; wh

问题补充：

The reason he was late for school was he had to send his mother to a hospital.

A. that; why

B. why; because

C. why; that

D. that; because

答案：

A. that; why

B. why; because

(答案→)C. why; that

D. that; because

解析：句意：他为什么会上学迟到的原因是他不得不送妈妈去医院。第一空填why。引导定语从句，先行词是reason，定语从句中缺少原因状语，第二空填that，连接表语从句，当主语是the reason的时候，表语从句用that连接，所以选C。