When working with additional information in a sentence, when should dashes be used instead of commas or parentheses?

How can a musical work be an argument

Analyze the central conflict and its in a story to discover the theme. resolution protagonist antagonist character

Read the excerpt below and answer the question.i ask, gentlemen, sir, what means this martial array, if its purpose be not to force us to submission? in this excerpt from his famous virginia convention speech, patrick henry employs which literary device? questiondeclarative statement