40. During the Revolutionary War, Lancaster, Pennsylvania, was the capital of the United States for one day in 1777, _________ there.
A. was when the Continental Congress stopped
B. when did the Continental Congress stop
C. the Continental Congress when it stopped
D. when the Continental Congress stopped
答案是D
為何是D呢?選項C為何不行呢?他不能當作整段句子的補充說明嗎?