Show that every infinite turing-recognizable language has an infinite decidable subset.

Read an excerpt from a speech by benito mussolini. italy! italy! entirely and universally fascist! the italy of the blackshirt revolution, rise to your feet; let the cry of your determination rise to the skies and reach our soldiers in east africa. let it be a comfort to those who are about to fight. let it be an encouragement to our friends and a warning to our enemies. it is the cry of italy which goes beyond the mountains and the seas out into the great world. it is the cry of justice and of victory. how does this excerpt support the idea that mussolini was a charismatic dictator? it shows how he used persuasive language to rally citizens. it explains his use of an aggressive foreign policy in europe. it shows how he used a secret police force to terrorize citizens. it explains how he used education to indoctrinate young people.