. Mary was so glad she was invited to attend the most important party.A. thatB. whereC. w

问题补充：

. Mary was so glad she was invited to attend the most important party.

A. that

B. where

C. why

D. when

答案：

A. that

B. where

C. why

(答案→)D. when

解析：考查连词。Where哪里，why 为什么，when 当什么时候，句意：玛丽如此的高兴当她被邀请参加一个重要的聚会的时候。所以选D。