This document discusses second and third conditional sentences. The second conditional is used to talk about hypothetical or improbable present/future situations using "if + past simple, would/wouldn't + infinitive". The third conditional is used to talk about hypothetical past situations and their consequences using "if + past perfect, would/wouldn't have + past participle". It provides examples of each conditional and notes that sometimes a past hypothetical situation with a present consequence is expressed using a mix of the two conditionals. Online exercises for practicing second and third conditionals are listed at the end.