问题补充：
Mathilde lost the necklace the evening when she and her husband took part in the palace ball.
A. until
B. at
C. on
D. in
答案：
A. until
B. at
(答案→)C. on
D. in
解析：介词辨析。Until直到……才； at在一点；on在某个平面，在具体某一天围。句意：马蒂尔德在他和她的丈夫参加宫廷舞会的那天晚上丢失了项链。结合语境可知是在具体某天的晚上，故用on。选C
