Question

why does roosevelt use repetition in his request for a declaration of war?
to highlight his own credibility
to provide alternative courses of action
to compare the experiences of countries
to emphasize the threat posed by japan

Explanation:

Repetition in a speech is often used to draw attention to a key point. In the context of a request for a declaration of war, emphasizing the threat (by repeating details about it) would be a strategic use of language to persuade the audience (in this case, likely Congress) of the necessity of war. Highlighting credibility would be more about using ethos - like referring to one's position or past good judgment. Providing alternative courses of action would involve presenting different options, not repetition. Comparing country experiences would involve contrast/comparison language, not just repetition. Since the goal of a war declaration speech is to show the danger (threat) that necessitates war, repetition would serve to emphasize that threat.

Answer:

to emphasize the threat posed by Japan