Preterite tense of regular verbs
I'm supposed to answer these questions negatively, indicating that what is asked has already happened. I can sort of mash a sentence together, but I'm not even remotely confident in it's structure. For example:
¿Vas a buscar una tienda de computadoras en el centro comercial?
To which I reply:
No, yo ya voy a buscé una tienda de computadoras en el centro comercial.
Now with that one I think I could at least get the idea across if I had to. But with the next one, ¡Estoy muy confundido!:
¿Vamos a encontrar muchas rebajas en el centro?
I don't even know what I'm supposed to conjugate. Does "ir" have preterite forms? I don't remember learning anything about that. The title of the lesson is "Preterite tense of regular verbs", but "ir" is irregular. ¡No comprendo¡
I'm not asking for anyone to do my homework for me, but can anyone help me understand how to do this?
3 Answers
No, yo ya voy a buscé una tienda de computadoras en el centro comercial.
No, no fue a buscar (only the verb infinitive is used after "a" in ir+a+verb)
No, ya busqué......
¿Vamos a encontrar muchas rebajas en el centro? (immediate future)
Are we going to find a lot of sales in the mall?
No, no encontremos....answering in the preterite. (No we did not find...)
No, no fuimos a encontrar... if you just want to make the periphrasis in the negative and preterit
No, we were not going to find....
Hmm there seems to be a couple of options here - 
If I understand correctly that the question is asked in the present tense but you must reply using the preterite tense (and still stick to the ir+a+inf form ) to say that something 'wasn't' done then only two things will change in the whole sentence:
If the question is - Vas a buscar.....? are you going to look for
Then the answer will just be No, no fui a buscar .... No, I didn't go to look: etc,
the no, no at the beginning
and using the preterite form of 'ir' - conjugating it to fit the person being spoken about is all you need to do
Preterite I went fui fuiste fue fuimos fuisteis fueron
But if you can reply just using only the preterite form without the ir+a construction then it's the same with the 'No, no' at the beginning;
and then you just add the preterite form of the verb which originally followed the 'ir+a' construction
- so for your original sentence the answer would be:
No, no busqué ......
Don't let the preterit intimidate you. If it helps, translate your sentences into English then into Spanish. For example:
Are you going to buy apples at the market?
No, I (already) bought them yesterday.
¿Vas a comprar manzanas al mercado?
No, (ya) los compré ayer.
The preterite is a simple past as in English: we went, we saw, we conquered, Caesar said, I saw it in a book. The imperfect is a past that occurs over an implied passage of time: we were going (used to go), we were seeing (used to see), we were conquering (used to conquer), etc.
Practice and use as many examples as you can think of.
