Bulgarian future perfect (ще съм отишъл – I will have gone) is used for actions that will have been completed by a certain moment in the future. Future in the past (щях да отида – I would go / I was going to go) is used for (hypothetical) future actions from a past perspective. Look at the following examples:
Ако можех да работя от вкъщи, (ще съм оставил / щях да оставя) колата на ремонт. (If I could work from home, I would leave the car for repairs.)
Ако не купим билети сега, до довечера (ще са свършили / щяха да са свършили). (If we don’t buy tickets now, by tonight they will have sold out.)
In the following exercise, choose the correct form (ще съм … or щях да …).