Answer:
Direct object pronouns are pronouns that represent the nouns that are directly acted upon by the verb. Indirect object pronouns stand for the noun that is the recipient of the verb's action.
As for formal VS informal, usted is the keyword. Whereas in english language being formal/polite has to do with the use of certain words, using usted (you) in spanish changes verbs in the sentence and makes the communication formal. Tú (you) is used informally. Usted is usually used for elders or those in higher up positions, like a teacher. Tú is usually used for friends.
Riesgos del alto consumo de sal.
<span>On November 19, 1493 Puerto Rico was discovered by Christopher Columbus on his second voyage to claim lands for the rulers of Spain, King Ferdinand and Queen Isabella. In 1493 the island was called Borinquen by the indians who lived there. Columbus named it San Juan Bautista.</span>
