Before I answer your particular questions about objects in English grammar, let us first formally define the terms “object,” “direct object,” “indirect object,” and “object of the preposition.”
Generally, an
object in a sentence is a noun, pronoun, or noun form (which can be a gerund, gerund phrase, noun phrase, or noun clause) that denotes the goal or result of the action of the verb. It can be any of three kinds: direct object, indirect object, or object of the preposition.
A
direct object is the entity acted upon by the doer of the action and directly receives the action of the verb. In the sentence “The mechanic fixed the car,” for example, the noun “car” is a direct object because it is directly acted upon by “mechanic,” which is the doer of the action of the verb “fixed.” Another way of saying this is that as direct object, the noun “car” directly receives the action of the verb “fixed.”
An
indirect object is the entity that receives the direct object of the sentence. It is the secondary goal of the action of its verb and is only indirectly affected by that action; another way of saying this is that the indirect object isn’t a direct receiver but only an intermediary or “pass-on” receiver of the action of that verb. In the sentence “Alex gave me a ride,” for example, the pronoun “me” is an indirect object because it’s only an indirect or “pass-on” recipient of the noun “ride,” which is the direct object of the sentence.
An
object of the preposition is a noun or pronoun introduced by a preposition to complete the meaning of a phrase that’s used to modify a sentence. This phrase is known as the
prepositional phrase and it consists of the preposition and its object as well as all other words modifying that object. For example, in the sentence “The unsavory revelations against the politician placed his integrity
under a cloud of doubt,” the noun phrase “a cloud of doubt” is the object of the preposition “under.” The entire prepositional phrase “under a cloud of doubt” then serves as a modifier of the noun “integrity.”
Now we are ready to take up the specific concerns you raised about these three kinds of objects in English.
Of course, you’re absolutely correct in your observation that (1) a direct object answers the questions “What is directly acted upon by the verb?” and “To whom is the action done?”, and that (2) an indirect object shows for or through whom the direct object is received. Thus, in the sentence that you gave as example, “She gave
me the report,” the pronoun “me” is undoubtedly an indirect object.
As to the admittedly baffling role of the pronoun “me” in the sentences that you presented in your posting, here are my observations and comments:
1. About the sentences “She gave it to me” and “She did it for me”In “She gave
it to me,” the pronoun “it” is actually the direct object of the verb “gave” while the pronoun “me” is the indirect object. Similarly, in the second sentence, “She did
it for me,” the pronoun “it” is the direct object of the verb “did” and the pronoun “me” is the indirect object. The confusing aspect of these two sentences is that their construction pattern is inconsistent with the pattern used when the direct object is a noun instead, as in the following sentences:
“She gave
me the laptop.”
“She did
me a favor.”
Note that in both of the sentences above in which the direct object is a noun, the indirect object “me” comes right after the verbs “gave” and “did,” respectively. When the direct object is changed to a pronoun, however, that sentence construction becomes untenable because it's so intolerably awkward and unnatural-sounding, as you can see below:
“She gave me
it.”
“She did me
it.”
To eliminate such quirkish sentence constructions, the English language took the recourse of putting the indirect object in a prepositional phrase instead of positioning it right after the verb, as follows:
“She gave
it to me.”
“She did
it for me.”
The two sentences above are obviously much smoother and better-sounding than in their previous construction. This is because in both sentences, the direct object “it” now comes right after the verb. In the case of the first sentence, “me” has become the object of the preposition “to”; and in the second, “me” has become the object of the preposition “for.” Even so, keep in mind that “me” still retains its grammatical function as the indirect object in both sentences.
2. What is “me” in the sentence “She told me about her dog”?In the sentence “She told
me about her dog,” the pronoun “me” is the direct object and there’s no indirect object at all. The object “her dog” isn’t functioning as an indirect object in that sentence but as the object of the preposition “about”; together, they form a prepositional phrase that serves as an adverbial complement in that sentence.
As to your last question, there’s really no rule to the effect that an indirect object can’t go without a direct object. The correct rule is that only sentences using a transitive verb can have or can accept a direct object, and that actually, a direct object doesn’t always require or doesn't always come with an indirect object. In fact, as you’ll discover soon enough, not very many transitive verbs in English need an indirect object at all when performing their action.
I guess this wraps up our discussion on the workings of the three kinds of objects in English grammar.