This document discusses conditionals in English, including first, second, and third conditionals. It provides examples of sentence structures and uses for each type of conditional. The first conditional is used to talk about possible present or future situations. The structure is "if/unless + present tense + will/won't." The second conditional talks about hypothetical or improbable situations using "if + past tense + would + infinitive." The third conditional refers to hypothetical past situations with "if + past perfect + would have + past participle." Examples are given to illustrate each conditional structure.