The sentence that shows an example of parallel structure is: "Felicity can bike 20 miles, can swim three miles, and run two miles, all without breaking a sweat."
However, it should be noted that this sentence could be improved for clarity and correctness by maintaining the same grammatical structure. A corrected version would be: "Felicity can bike 20 miles, swim three miles, and run two miles, all without breaking a sweat." This correction ensures that all verbs are in the same form, which is essential for true parallel structure.