"Do you like tennis or soccer?"
Translation:¿A ti te gusta el tenis o el fútbol?
my response was "te gusta tenis o futbol?" and i got it wrong because I needed el before tenis. However, correct response did not put el before futbol. Why not both?
I put el before both as illogical otherwise. Not only accepted, it is given as the correct answer now. Must have been an error. The articles are def required I think because we mean tennis or football in general and they are actually the subjects of this, to English ears, back-to-front sentence.
¿Te gusta el tenis o el fútbol? = Do you like tennis or soccer?
"A-phrases” are used to clarify or emphasize object pronouns.
Since the indirect object pronoun te is as clear as can be, Duo's "a-phrase" must be there to emphasize the te. Nothing in the context asks for emphasis, so the sentence should be accepted as correct without the "a-phrase."
Adding the "a-phrase" here doesn't change the translation, unless you want to show the emphasis in your English translation with italics, underlining, etc.: "Do you like tennis or soccer?"
"A-phrases" are very important when they add information (clarify) the object pronoun:
Le gusta el tenis. He/She/You (formal) like(s) tennis.
A él le gusta el tenis. He likes tennis.
A ella le gusta el tenis. She likes tennis.
A usted le gusta el tenis. You like tennis.
When I see or hear the A ti, I think, "And how about you? Do you like tennis or soccer (like I do?)" It often suggests the questioner is looking for agreement or comradery.