Voted Best Answer
Jun 23, 2013 - 02:02 PM
First, I believe they are all pronouns, not prepositions, and all generally translate in English as "it.". I think the issue is whether when you substitute, you are substituting for a work that is a direct object (le, la, les) or the subject of a sentence or clause (il, elle, etc.). In the example you gave "la" is the direct object of "manger". Your next sentence could be "Elle est delicieuse." Now, "elle" is the subject of "est."