Confusion with pronouns

Confusion with pronouns
 

Hola todos,
I would be very greatful if you could help with the following question please.
If I wanted to say the following in spanish "You used to buy them for me" then i assume I can say either;
1) me las comprabas
2) las comprabas para mi

By this logic then if I wanted to say "He is preparing it for me" in spanish could i say either;
a) me lo prepara
B) lo prepara para mi

It is answer "a)" above which is confusing me as I believe it may be incorrect? If it is indeed incorrect can you please advise as to why it differs in construction from answer "1)" above)
Thank you very much in advance

Nilo

All your options are correct. In fact, natives usually use 1) and a).
Note: the structure "use to" is translated into Spanish as "soler".

A pleasure.

Thank you very much for your help on this, it was driving me crazy! Have a good weekend...

I agree with Julvenzor: all 4 of these sentences are correct, and 1 and a are the more common ways to say each pair.

However, something you wrote confuses me:
You seem to think that 1) and a) differ in construction, when they actually have the same construction:

1) me las comprabas
a) me lo prepara

The construction is:

indirect_object_pronoun direct_object_pronoun conjugated_verb

Hi wrholt,
First of all thanks a million for your reply on this. I am sorry for the confusion in that sentence, what I actually meant to ask was that if "a)" was not correct and "1)" is correct then as they are of the same construction why should the rules be different? My confusion really started as a result of listing to both the Michel Thomas audio course (he seems to favour the "2)" and "B)" construction) and the Learning spanish like crazy audio course where its always the "1)" and "A)" approach. I was initially unsure as to whether or not there was a reason for the approaches differing hence my confusion.
Thanks a million,
Nilo

I am sorry, I am not really sure what you mean with this "construction", maybe this will put into perspective so that you can assess if this was indeed what you wanted to ask.

1) me las comprabas = (you) bought them for/from me

a) me lo prepara = (command/imperative) prepare it for me/he she prepares it for me

Would this help you to discern what is it that you are after? Or, am I confusing you?

Buenos dias Chileno,
Sorry my initial question was confusing. By construction i meant the following;
1) Me las comprabas - So in my mind "constructed" like "(Me) + (Them) + (used to buy)
2) Las comprabas para mi - "(Them) + (used to buy) + (for me)
Sorry for my confusing wording of the initial question and thanks for your reply.
Nilo

OK. That's good then. No need to apologize, which is natural when one is learning a new language. I just wanted to make sure you understood my point too. :)

Just a grammatical note to avoid confusion: "me lo prepara", although it can be used colloquially as a mild imperative formula for the pronoun "usted", is not an imperative conjugation. The imperative form for "usted" should be "prepáremelo" and the one corresponding to "tú" is "prepáramelo".
The example in the context provided by the OP, is just a declarative sentence stating that a third person prepares something for me.

@Elwapo: I think the answer to your question has been very clearly provided by wrholt. :)

Thanks Angelica