It is a very colourful and useful worksheet of the 3rd conditional with a brief explanation (3rd Conditional is used to talk about actions, and if they have happened, the consequence would have been done. So, we use this conditional in order to talk about unreal things that could have happened, and if they have happened the consequence would have been done).
We form it: IF+ PAST PERFECT, would+ PRESENT PERFECT. (had + V3) (have + V3)
E.g. If I had seen you, I would have said hello. and several excercises to practice. hope you like it!