这是一个什么句，是怎么翻译的,是如何划分句子成分的,thanks
133. ____ I had time, I would have run around that la again. A. If B. Unless C. Had D. When
C. Had I had time, I would have run around that lake again. 虚拟语气,如果我有时间,我会再绕着湖跑 Had,have的过去式:如果,要是