It makes comer a reflexive verb, comerse. This can be done to intensify the meaning of a verb. In this case, from ate eleven sandwiches to "gobbled up" eleven sandwiches. Or so one of my Spanish grammar books tells me.
From your comment here, I now understand that "se" is a suffix appended to some form of the verb, and that it can be broken off and used elsewhere in a statement or sentence, the position of "se" can be transposed, it is fluid. I understand the reflexive quality of "se" and the importance of the nuances that drive its use. In one discussion somebody said "so we throw se in there", now I understand this. Thanks.
I have to agree with joarvat. "Se comieron once emparedados" could mean "Eleven sandwiches were eaten," with se comieron as the passive past tense plural conjugation of comer.
Comerse can also mean "eat up" instead of just "eat" (for more emphasis, as some people have already posted).
In my mind, the two most correct translations are "Eleven sandwiches were eaten" and "They ate up eleven sandwiches."
I think that is actually the most correct translation, but the problem is that at this point in the course we are not supposed to know how to construct a past passive tense, and so it is not accepted.
I don't agree. Comieron tells us that they (plural) ate sandwiches which is not translated in the sentence "eleven sandwiches were eaten"
Couldn't 'comieron' tell us that they (plural, as in the sandwiches) were eaten?
No. ¨Comieron¨ means ¨they ate.¨ (or ¨You ate¨ if you´re talking formally to at least two peopl)
It probably isn't, but once it's present, like people said above me (i did not know this before reading this) - it intensifies the verb following it.
So, to clarify, comer and comerse are two different verbs that are both related to eating, sí? Comerse is reflexive hence requiring the 'se' in this sentence ... is that right?