______ experiment took as long as five months and turned out ______ great success.
A.The; /B./; aC.The; aD.The; the在线课程C
句意：此实验持续达5个月之久，结果成功了。experiment为单数名词，无论在句中表泛指还是表特指，都需与冠词连用，不能与零冠词连用，故排除B项；在本句中，success--person or thing that succeeds成功者；达到目的的人或事物，为可数名词，且在本句中表泛指，故与不定冠词连用。如：①He wasn't a success as a teacher.他不是个好教师。②Of her plays, three were successes and one was a failure.她的剧作有三部成功，一部失败。