"Esto interesa a mucha gente."
Translation:This is of interest to many people.
Yes. The Spanish preposition "a" has to be before the direct object if this is a person. Some people then name the preposition the personal a.
The "a" in Duo's sentence and Esto interesa a los burros is not personal. It is there because interestar has indirect object which always is preceeded by the preposition "a" if a noun.
Because this = esto, that = eso
see Demonstrtives: http://studyspanish.com/grammar/lessons/demonstratives
Renamarie, yes - I spoke the Spanish phrase, and what you said WAS the answer that Duo gave. I came to the forum to see why people thought the "a" was there.
However, twice on this lesson, Duo-girl has not liked my spoken answers, and they were easy words (ellos and a) that I've been pronouncing correctly since the beginning! I barely paused on the "a" because that's way she said it, and she only gave me an "almost correct," and put the "a" in red, indicating that she didn't like the way I said it. :-(
Today (Sept 2016) it was a "Type what you hear" version of this exercise.
I heard "esto interesa ha mucha gente" (which sounds exactly the same as DL's version). It makes sense and should have been accepted, but it was marked wrong. I have reported the error.
Why is it not "Esto le interesa a mucha gente"? As written, I understand it as "This is of interest to a lot of people", where "to be of interest" is the verb phrase. I know the two translations mean the same thing, but I would have thought the form requiring the indirect object pronoun "le" would be more common. Please correct me if I'm wrong, but I thought in that case use of the IO pronoun was compulsory.