Final answer:
The prepositions 'por' and 'para' have different meanings and uses in Spanish. 'Por' is used to indicate movement through, duration of time, cause or reason, and to express gratitude or apology. 'Para' is used to indicate purpose, destination, deadline, or recipient.
Step-by-step explanation:
In Spanish, 'por' and 'para' are both prepositions, but they have different meanings and uses. 'Por' is often used to indicate movement through, duration of time, cause or reason, and to express gratitude or apology. On the other hand, 'para' is commonly used to indicate purpose, destination, deadline, or recipient.
Looking at the options given, the correct sentence that should use 'por' instead of 'para' is: 'Voy a caminar por las calles.' In this case, 'por' is used to indicate movement through the streets.
Learn more about Prepositions in Spanish