Second Conditional (Unreal Present/Future) · Structure: If + Past Simple, ... would + verb · Use: For hypothetical situations in the present or future that are impossible or unlikely. Examples: · If gravity stopped suddenly, everything on Earth would float away. · If the human body could photosynthesize, we would not need to eat food. · Scientists would discover more cures if they had unlimited funding. Third Conditional (Unreal Past) · Structure: If + Past Perfect, ... would have + past participle · Use: For imagining different outcomes in the past (things that did not happen). Examples: · If the asteroid had not hit Earth 66 million years ago, dinosaurs would not have become extinct. · If Marie Curie had known about the dangers of radiation, she would have taken more precautions. · The climate crisis would have been be less severe if we had switched to renewable energy sooner. Key Difference: Use the 2nd for imagining the present/future, and the 3rd for regretting or changing the past.