non dubito quin pater venturus sit, I do not doubt that my father will
    come;

    non dubitabam quin pater venturus esset, I did not doubt that my
    father would come.

4.  Where the verb has no Future Active Participle, or where it stands in the passive voice, its Future character may be indicated by the use of the particles mox, brevi, statim, etc., in connection with the Present and Imperfect Subjunctive; as,—­

    non dubito quin te mox hujus rei paeniteat, I do not doubt that you
    will soon repent of this thing;

    non dubitabam quin haec res brevi conficeretur, I did not doubt that
    this thing would soon be fnished.

TENSES OF THE INFINITIVE.

270. 1.  The tenses of the Infinitive denote time not absolutely, but with reference to the verb on which they depend. Thus:—­

  a) The Present Infinitive represents an act as contemporaneous with the
  time of the verb on which it depends; as,—­

    videtur honores adsequi, he seems to be gaining honors;

    videbatur honores adsequi, he seemed to be gaining honors.

  b) The Perfect Infinitive represents an act as prior to the time of the
  verb on which it depends; as,—­

    videtur honores adsecutus esse, he seems to have gained honors;

    visus est honores adsecutus esse, he seemed to have gained honors.

  c) The Future Infinitive represents an act as subsequent to that of the
  verb on which it depends; as,—­

    videtur honores adsecuturus esse, he seems to be about to gain
    honors;

    visus est honores adsecuturus esse, he seemed to be about to gain
    honors.

2.  Where the English says ‘ought to have done,’ ‘might have done,’ etc., the Latin uses debui, oportuit, potui (debebam, oportebat, poteram), with the Present Infinitive; as,—­

    debuit dicere, he ought to have said (lit. owed it to say);

    oportuit venire, he ought to have come;

    potuit videre, he might have seen.

  a.  Oportuit, volo, nolo (and in poetry some other verbs), may take a
  Perfect Infinitive instead of the Present; as,—­

    hoc jam pridem factum esse oportuit, this ought long ago to have been
    done.

3.  PERIPHRASTIC FUTURE INFINITIVE.  Verbs that have no Participial Stem, express the Future Infinitive Active and Passive by fore ut or futurum esse ut, with the Subjunctive; as,—­

    spero fore ut te paeniteat levitatis, I hope you will repent of your
    fickleness (lit. hope it will happen that you repent);

    spero futurum esse ut hostes arceantur, I hope that the enemy will be
    kept off.