Definition:  Indirect question is used to express a question someone has posed, without using a direct quotation.

    Quid est?    What is it?
    Direct Question - gives the exact words of the speaker

    Rogavit quid esset.    He asked what it was.
     Indirect Question - adapts the question to the sentence in which it is being quoted.
 

Formation:  Indirect question is regularly introduced by an interrogative word and takes its verb in the subjunctive.

    1)    The subjunctive in indirect question follows the regular rules for sequence of tenses.

            a)  Indirect question referring to future time take the subjunctive of the periphrastic
                 conjugation to avoid confusion that the present subjunctive could cause.
               Dico quid facturus sim. - I tell you what I will do.
                (quid faciam? - What will I do?)

            b)  The deliberative subjunctive remains unchanged in indirect question, except
                 occasionally in tense.
               Neque satis constabat quid agerent. - It was not very clear what they were to do.
                (Quid agamus? - What should we do?)

    2)    In certain cases the indirect question can take the indicative:

            a)  In early Latin and in poetry, the indicative can be used.
               Dic, quid est? - Tell me, what is it?
                 (Dic quid sit. - Tell me what it is.)

            b)  The indicative is used following nescio quid when it is used in its indefinite sense.
               Nescio quid maius nascitur Iliade. - Something, I know not what, is coming to
                 birth, greater than the Iliad

            c)  There are other colloquial uses that will take the indicative, as they are used adverbially.
               nescio quomodo - I know not how = strangely
               mirum quantum - It is marvelous how much = marvelously

    3)    The subject of an indirect question is often attracted into the main clause as an object
           (Accusative of Anticipation)
               Nosti Marcellum quam tardus sit. - You know how slow Marcellus is.
                (Nosti quam tardus sit Marcellus.)

    4)    The particles used in indirect question are the same as in direct questions, although
            some have different nuances.

            a) num, which anticipates a negative answer in direct question, loses this negative
                 force in indirect question and can be translated as "whether."
               Rogant num velis venire. - They ask whether you wish to come.

            b) si is also translated as "whether" in indirect question.
               Ibo, visam si domi est. - I will go to see whether he is home.