The party last night was _______success. We sang and danced until it came to _______end at twelve.
A. a ,the B. a, an
C.the, an D. /, an

success可数或不可数都会有：
suc.cess
AHD:[s…k-sµs“]
D.J.[s*k6ses]
K.K.[s*k6sWs]
n.（名词）
The achievement of something desired, planned, or attempted:
成功：对预期的、计划的、尝试的事物的达到：
attributed their success in business to hard work.
将他们生意上的成功归因于辛勤的工作
The gaining of fame or prosperity:
成功：声誉或繁荣的获得：
an artist spoiled by success.
被成功冲昏了头脑的艺术家
The extent of such gain.
成功程度：此类获得的程度
One that is successful:
成功的人（或物）：
The plan was a success.
这个计划是一个成功
Obsolete A result or an outcome.
【废语】 结果或效果

Latin successus [from past participle of] succ¶dere [to succeed] * see succeed
拉丁语 successus [] 源自succ¶dere的过去分词 [成功] *参见 succeed

你经常使用这个词会帮助你记住它的用法。