Fill in the Blanks Third Conditional Challenge1 (B1+)Online version Third conditional practice. by Centro de Autoacceso Unidad Los Uribe FCA 1 In English , talks about events and their impossible results today . We form it with if + , then would have + , I . Students use this structure to express or to imagine that . The idea contrasts with real past alternatives and emphasizes that did not actually occur . Notice that the main clause is not about the present , but about how the past could have changed the present or future .