Final answer:
Roosevelt uses the rhetorical device of parallelism in this passage.
Step-by-step explanation:
The rhetorical device that Roosevelt uses in the passage is parallelism.
Parallelism is the repetition of the same pattern of words or grammatical structures to emphasize ideas and create a balanced and memorable effect. In the passage, Roosevelt uses parallel structure to call attention to the ideas in his speech and organize his support for the idea that the United States works collaboratively for 'the success of liberty'.
Example of parallelism in the passage: 'Ask not what your country can do for you but what you can do for your country.'