The thing to remember here is that Chinese doesn't have tenses -- it conveys this information differently. Conditionals and counterfactuals are formed by including the conditions ("哎，我要是穿越时空以后没踩到那只蝴蝶..." / "If only I hadn't gone back in time and stepped on that butterfly...") and then the results ("...现在就不会到处都是恐龙了" / "...there wouldn't be dinosaurs all over the place today."). As with most other things in Chinese, the context will carry the burden of information that English and other languages tend to put on the verb.

(Early morning; insufficient caffeine; all disclaimers apply.)