If this has been discussed in another thread, I'm having trouble finding it. But I find it hard to believe that I'm the first to ask. I'll go ahead anyway. If you know of another appropriate thread, please point me in that direction........
If I want to say that something started in the past and is ongoing, I can say:
Estudio español hace un año.
Or
Hace un año que estudio español.
Now, a book that I'm using to study says that it would also be equivalent to say:
Estudio español desde hace un año.
But I have a friend, born and raised in the United States, but who now lives in Bolivia (for quite a few years now) ... and this friend insists that you cannot use "desde" with "hace" for time phrases. She insists that "desde" means that something happened "from" a certain time. She tells me that you can use one or the other but not both. So that is my first question. Is my phrase with "desde hace" equivalent to the other two phrases?
My next question is how to express something in the past that also ended in the past. If I want to say that I studied Spanish in college 20 years ago, could I also say:
Estudié español hace veinte años en la universidad.
For some reason I seem to remember being told that this is how to say it. But then how do you distinguish between the action that hasn't yet ended and the action that ended twenty years ago?