Peter was so excited he received an invitation from his friend to attend the wedding.
A. where
B. that
C. why
D. when
网友回答
A. where
B. that
C. why
(答案→)D. when
解析：考查状语从句。状语从句：when he received an invitation from his friend to attend the wedding.修饰整个一句话Peter was so excited句意：当他收到来自朋友的婚礼请柬的时候，他非常高兴。根据句意说明D正确。