English exercise: conditionals (B2)

The zero conditional (if + present, present) is for facts and things that always happen: "If you heat ice, it melts." The first conditional (if + present, will + verb) is for real possibilities in the future: "If it rains tomorrow, we will stay home." Unless means if not, so it follows the same pattern. The second conditional (if + past, would + verb) is for situations that are unreal or unlikely now: "If I had more time, I would learn the piano." In formal English, were is used for every person: "If I were you..."

The third conditional (if + past perfect, would have + past participle) is for imagined changes to the past: "If we had left earlier, we would have caught the train." Mixed conditionals combine the two: an unreal past with a present result ("If I had taken that job, I would live in New York now"), or an unreal present with a past result ("If he were more careful, he wouldn't have made that mistake"). Look at the time words in each half of the sentence to decide which form fits.