Here's why:
* Gerunds are verb forms ending in "-ing" that function as nouns. They can be the subject, object, or complement of a sentence.
* Indirect objects receive the direct object. They are typically nouns or pronouns.
* Objects of prepositions follow a preposition. Prepositions show the relationship between a noun or pronoun and another word in the sentence.
Example:
* Incorrect: "I gave *running* the ball."
* "Running" is a gerund, but it cannot be the indirect object because it doesn't receive the direct object "ball."
* Correct: "I gave the ball *to running*."
* "Running" is the object of the preposition "to."
In summary:
* Gerunds can be objects of prepositions.
* Gerunds cannot be indirect objects.