Third Conditional Explanation With the third conditional we talk about the past. We talk about a condition in the past that did not happen. If
+ Past Participle(had or hadn't) "," + Would(not) have + verb in participle
If I had gone to school , I would have understood it. If I hadn't gone to school , I wouldn't have understood it. Would(not) have + verb in participle + If
+ Past Participle(had/hadn't)
I would have understood it if I had gone to school. I wouldn't have understood it if I hadn't gone to school.