【题目】— Did you have a good time at Laura's birthday party?
— Yes, indeed. It's several years ________ I enjoyed myself so much.
A.when
B.before
C.since
D.that

【答案】C
【解析】考查从属连词。“It is + 一段时间 + since + 从句”意思是“自......发生以来已经一段时间了”。句意：几年以来我才玩得如此开心。根据句意，所以答案是C。