【题目】While working in Kunming, he checked the weather each morning for months ________he realized it would be the same every day.
A. when B. after C. before D. since
在线课程【答案】C
【解析】考查连词。句意：当在昆明工作的时候，在他意识到每天天气都一样之前，连续几个月来他都在早上查天气。when当……时候；after在……之后；before用作连词时，意思是“在……之前”；since自从……，故选C。