That was really a splendid evening. Its years I enjoyed myself so much.A. whenB. thatC. b

问题补充：

That was really a splendid evening. Its years I enjoyed myself so much.

A. when

B. that

C. before

D. since

答案：

A. when

B. that

C. before

(答案→)D. since

解析：解析对时间状语从句的考查:由since引导的时间状语从句,如从句中的谓语动词是持续性动词,动作从结束时算起,本句表示的意思是“我已有多年没有玩得如此愉快”。如从句中的谓语动词是瞬间动词,动作从开始时算起,如：It’s three years since he joined the army.意为“他参军已经三年了。”根据句子的时态与句意,选D。