Translation:The boy always wants to watch television.
As no expert answer has appeared, I will try. First, in this case the television is not the subject, in which case it would need a definite article. Next, one must note that in this sentence, you are not really saying that one is watching the television set, you are saying that one is watching programs on the television. Television programs exemplify uncountable nouns. Generally, uncountable nouns don't require a definite article in Spanish. If you were really watching the television set (for signs of smoke or appearance of a mouse from within) you would use the definite article because a television set is an example of a countable noun.
I depends on the situation. You can't say ver exactly means to watch and mirar exactly means to look at, because sometimes Spanish uses a different word than English would. In other words, you can't translate them directly over like that. I've learned which to use based on experience and context.
I'm sorry, that isn't a great thing for a new learner to hear, but that's the truth of it, and this won't be the last time you run into that. The best help I can give is that to see is almost always ver. At least, in every instance I can think of, you would use ver where you would say see.
i.e. I can't see it=No puedo verlo.
The boy always wants to watch television. = El niño siempre quiere mirar televisión.
For why television is television not la television see DuncanJBrown post here: https://forum.duolingo.com/comment/27692386?comment_id=31312826
Television is always boring = La televisión siempre es aburrida.
Most verbs normally require the subject to have a determiner, so in "Television is always boring", television is the subject so la television is the correct Spanish.
boy is the subject of the other sentence , and follows the same rule.
What should Ava?
This is the USER forum. We cant see what your answer was.
There is nothing we can do unless you copy and paste your answer so that we can help you check it. It would be useful to have Duo's response too.
If you did happen to provide a correct translation and it is not accepted, this link should help:
How do I report a problem with a sentence or translation?
Already asked and answered:
Please don’t use Duolingo to...
Spam the forum or people’s streams
Leaving a trail of irrelevant, abusive, illegal, or nonsensical entries in forums or anywhere on Duolingo may get your account deleted. This includes not only creating posts without substance, but any type of spamming. It's okay to share external resources and links. But just like with copyrighted and pirated materials, you should know that spamming, referral code hocking, advertising, and excessively promoting products/services is not acceptable and such posts and references can be removed without warning.
Begging for lingots in irrelevant places falls under this rule. You'll get plenty of lingots anyway if you use Duolingo for its intended purpose: learning langauges.