Allen and Greenough's New Latin Grammar for Schools and Colleges
J. B. Greenough, G. L. Kittredge, A. A. Howard, Benj. L. D'Ooge, Ed.

1. dīcō quid faciam, I tell you what I am doing.
2. dīcō quid factūrus sim, I tell you what I will (shall) do.
3. dīcō quid fēcerim, I tell you what I did (have done, was doing).
4. dīxī quid facerem, I told you what I was doing.
5. dīxī quid fēcissem, I told you what I had done (had been doing).
6. dīxī quid factūrus essem, I told you what I would (should) do (was going to do).
7. dīxī quid factūrus fuissem, I told you what I would (should) have done.

[*] a. Indirect Questions referring to future time take the subjunctive of the First Periphrastic Conjugation:—

1. “prōspiciō quī concursūs futūrī sint ” (Caecil. 42) , I foresee what throngs there will be. [Direct: quī erunt ?]
2. “ quid sit futūrum crās, fuge quaerere ” (Hor. Od. 1.9.13) , forbear to ask what will be on the morrow. [Direct: quid erit or futūrum est ?]
3. “posthāc nōn scrībam ad tē quid factūrus sim, sed quid fēcerim ” (Att. 10.18) , hereafter I shall not write to you what I am going to do, but what I have done. [Direct: quid faciēs (or factūrus eris )? quid fēcistī ?]

[*] Note.--This Periphrastic Future avoids the ambiguity which would be caused by using the Present Subjunctive to refer to future time in such clauses.

[*] b. The Deliberative Subjunctive (§ 444) remains unchanged in an Indirect Question, except sometimes in tense:—

quō mē vertam nesciō; (Clu. 4), I do not know which way to turn. [Direct: quō mē vertam ?]
1. “neque satis cōnstābat quid agerent ” (B. G. 3.14) , and it was not very clear what they were to do. [Direct: quid agāmus ?]
2. “nec quisquam satis certum habet, quid aut spēret aut timeat ” (Liv. 22.7.10) , nor is any one well assured what he shall hope or fear. [Here the future participle with sit could not be used.]
3. incertō quid peterent aut vītārent (id. 28.36.12), since it was doubtful (ablative absolute) what they should seek or shun.

[*] c. Indirect Questions often take the Indicative in early Latin and in poetry:—

vīneam quō in agrō cōnserī oportet sīc observātō; (Cato R. R. 6.4), in what soil a vineyard should be set you must observe thus.

[*] d. Nesciō quis , when used in an indefinite sense (somebody or other), is not followed by the Subjunctive.

So also nesciō quō ( unde , an, etc.), and the following idiomatic phrases which are practically adverbs:—

1. mīrum (nīmīrum) quam, marvellously (marvellous how).
2. mīrum quantum, tremendously (marvellous how much).
3. immāne quantum, monstrously (monstrous how much).
4. sānē quam, immensely.
5. valdē quam, enormously.

Examples are:—

1. “quī istam nesciō quam indolentiam māgnopere laudant ” (Tusc. 3.12) , who greatly extol that freedom from pain, whatever it is.
2. “ mīrum quantum prōfuit ” (Liv. 2.1) , it helped prodigiously.
3. “ ita fātō nesciō quō contigisse arbitror ” (Fam. 15.13) , I think it happened so by some fatality or other.
4. nam suōs valdē quam paucōs habet (id. 11.13A. 3), for he has uncommonly few of his own.
5. sānē quam sum gāvīsus (id. 11.13A. 4), I was immensely glad.
6. “ immāne quantum discrepat ” (Hor. Od. 1.27.5) , is monstrously at variance.