The reason he refused to attend the meeting was that they didn’t give him an invitation ea

问题补充：

The reason he refused to attend the meeting was that they didn’t give him an invitation earlier.

A. how

B. which

C. why

D. because

答案：

A. how

B. which

(答案→)C. why

D. because

解析：句意：他拒绝参加会议的原因是他们没有提前给他请柬。这里是定语从句，先行词是reason，关系词why在从句中作状语，故选C。