about future tenses a sentence like the following
could come to mind
Cuando vendrás, te lo regalaré.
= When you will come,
I will give it to you.
That is simply wrong. If the main clause indicates,
that the action is not yet realised then after cuando
always, the subjuntivo
has to be used. In this example the main clause (te
lo regalaré) indicates that the action
was not yet realised therefore it has to be subjuntivo.
right version is
te lo regalaré. =
When you come, I will give it to you.
When talking about the interrogative pronoun cuándo
this does not apply. If you might remember the radio
waves of long gone years...
tu vendrás, cuándo, cuándo,
cuándo = Tell
me when you will come, when, when, when
(For those ones who had not the pleasure of ever hearing
this hit, don't mind it is no loss, but it is rather valuable
for grammar lessons)
To be kept in mind is that the impersonal phrases can
be used in any tense also in the future tense.
que decírselo. = He will have
to be told. Habrá que
gastar mucho dinero para restablecer la
infrastructura. = It will have
to be spent a lot of money to reconstruct