les gusta

Question

I have the test question: A ustedes no ________ este documental, ¿verdad? The answer is "les gusta".  Why isn't it "les gustan"?

Inma Sánchez · Accepted Answer

Hola Scott
With gustar, we match the verb with the thing that is liked (which is the subject of the sentence), so, if what one likes is singular, e.g, el chocolate, la mermelada, la cultura japonesa, etc... you need "... gusta....". If what one likes is plural, e.g las películas de acción, los plátanos, las arepas...., then you need "... gustan..." 
In this case, we have "este documental" as the subject (singular thing), so it should be "les gusta..."
If you´re confused because you see a plural pronoun "les" and this makes you think you need the verb in the plural too, it´s important to remember that the pronoun is matching the person who does the liking, in this case "ustedes", and the verb is agreeing with the thing that is liked. 
I hope this clarified it.
Saludos
Inma