Casi vs. a casi

Casi vs. a casi
 

I was talking with a Peruvian friend and I said "Él vive casi dos horas de aquí..." and she corrected me and said "Él vive a casi dos horas de aquí...".

We spent some time over the following couple of days with her giving me examples of when to use "a casi" vs. just "casi". I didn't really follow except for the following: (1) mostly when you're talking about time you use "a casi" and (2) if you are answering a question that uses "a ¿¿¿???" you answer with "a casi" instead of "casi".

Is it possible to get an explanation of what would trigger "a casi" vs. just "casi"? And could you give me some (lots of?) examples to go with that? Thanks!!

I never thought about it. I'll have a try. We use "a casi" when "a" is needed in the sentence without "casi". Hopefully, that's all.


La casa está a dos kilómetros/horas de distancia.
La casa está a casi dos kilómetros/horas de distancia.

Estuve andando dos horas.
Estuve andando casi dos horas.

Hicimos un viaje de 1000 kilómetros.
Hicimos un viaje de casi 1000 kilómetros.

Wow - okay, so that uncovers something else that I don't understand. In each of your sentences given, I don't understand why you would or wouldn't use "a". Hmmm.....

Distances use "a" ("está a mil millas de distancia"), including everything that is used as a distance ("está a dos horas en automóvil" where in fact that "a" shows we are speaking in terms of distance).

La casa está a dos horas en automóvil (The house is a two hours drive away)
La casa está dos horas en automóvil (The house is two hours in the car :crazy:)

Each one is a set expression, more or less. Sticking with Don José's examples:

1. To say "to be (located) [some distance] from here", one must say "estar a [distance]". It doesn't matter whether the distance is exact ("Está a dos kilómetros") or approximate ("Está a casi dos kilómetros"): the expression requires using the preposition "a".

2. To say "to walk (for) [time span]", one says "andar [time span]": no preposition is required. It doesn't matter whether the time span is exact "estuve andando dos horas" or approximate ("estuve andando casi dos horas"): the expression does not require a preposition.

3. To say "to take a trip of [distance]", one says "hacer un viaje de [distance]". It doesn't matter whether the distance is exact ("hicimos un viaje de 1000 kilómetros") or approximate ("hicimos un viaje de casi 1000 kilómetros"): the expression requires using the preposition "de".

The word "casi", like English "almost", modifies some type of measurement. Whether one uses a preposition before that measurement depends on the context in which one is using the measurement: the context determines whether a preposition is required: the presence or absence of the word "casi" is irrelevant.

Okay - thanks, all. I'm working on this ... trying to wrap my head around it. I get that "casi" has nothing to do with it, but understanding when to use "a". Thanks for all of these great answers!! :)