Why Imperfect subjunctive?

Question

Ojalá yo ________ un hijo a los 33 años. I hope I have a son by the time I'm 33.(HINT: Conjugate "tener" in El Imperfecto de Subjuntivo)For “Have a son”, why not use subjunctive? Doesn’t Imp subj mean HAD a son?Thanks

Accepted Answer

Hola Shirley
We are using the subjunctive. But in English it wouldn't work if we said "I hope I had a son by the time I'm 33", because we are talking here about a future event, so we have to say it in the present "I hope I have..." 
In Spanish, you can either use the present subjunctive or the imperfect subjunctive (ojalá tenga...- ojalá tuviera); the imperfect subjunctive would create the idea of "less probability".
We are testing conjugation here so we can only admit "tuviera" -the hint is asking for conjugation of the imperfect subjunctive of tener.
I hope this clarified it.
Saludos
Inma