Questions about Indirect Object Pronouns
Q: Why is it te doy el libro (a ti) and NOT le doy el libro (a ti)?
Remember that the indirect object pronoun must agree in person and number with the indirect object, which occurs after the preposition.
Q: Why is it Él me vendió la computadora and NOT Él vendió me la computadora?
Object pronouns usually come before the verb in Spanish, except for in affirmative commands and optionally in compound verb phrases.
Q: Why is it le quiero regalar un dulce a la niña m and NOT la quiero regalar un dulce a la niña?
Because a la niña is the indirect object (answers the question "to whom do you want to give a candy?"), you must use the indirect object pronoun le, not the direct object pronoun la.
Q: Why is it quiere prestarnos su casa en la playa OR nos quiere prestar su casa en la playa but NOT quiere nos prestar su casa en la playa?
The pronouns should not be placed in the middle of a verb phrase. They can go before the main verb or attached to the infinitive in this case.
Q: Why is it estaban comprándote un helado and NOT estaban comprandote un helado?
When the object pronouns are attached to the present participle (or affirmative commands), you must add an accent where the stress normally falls.