Infinitives Can Be Perfect Too

From the mailbox:

Your e-mail lessons are wonderful. However I am now confused by the "perfect infinitive." When and how is it used? Where are object pronouns placed? When do (and which) prepositions precede it?

The perfect infinitive is simply haber followed by a past participle, just as the perfect verb tenses are formed by a conjugated form of haber and a past participle. To answer your question more fully, I've written a new Spanish lesson on perfect infinitives that explains them more fully and gives about a dozen examples of how they're used. Although they aren't an extremely common feature of Spanish, they're probably used a bit more than they are in English.