I wil try to explain it like this:
Do you want to see the shirt? ¿Quieres ver la camisa? (I will show it to you)
Do you want to see the bear? ¿Quieres ver al oso? ( You will meet it)
Do you want to see your uncle? ¿Quieres ver a tu tío ( You will see each other face to face)
Some of the other sentences with "ver" don't use the "a," so I don't think the verb requires it. Maybe it's a matter of preference when it comes to animals, rather like the choice in English to refer to animals using either the pronoun "it" or gendered pronouns "he" and "she."
I understand the specificity of this translation in Spanish, but if you were translating "Ustedes quieren ver al oso?" to English it would still translate to "Do you want to see the bear?" and both Spanish translations still ask the same thing; so disregarding the specific tu'/ustedes "want to see the bear?" seems to be an acceptable translation in English at least. Or is this completely incorrect because "Want to see the bear?" to from English to Spanish would be a different tense?
Or is it wrong because it is ambiguous to Spanish speakers?
I see, thank you for your replies. Sorry for not being clear, I meant you know how you ask someone (in English) "Want a beer?" Don't you really mean "(subject) want a beer?" but you do not actually include the subject? So I'm saying contextually, you wouldn't need to include the subject in the sentence to get across who (the subject) you are speaking to. That's also the reason why I asked the initial question of why "Want to see the bear?" is not an acceptable English translation. Does that make any sense?
Yes, now I understand what you mean. If you are speaking directly to someone informally, and you leave out the subject of the sentence (you), the person spoken to would know that you are asking him, and not someone else. However, I don't think Duolingo is going to accept this as a translation. The answers to the questions are probably fixed in the system, and not subject to change.
A bit late with my reply, but see Wikipedia's article related to your question. The whole article is an interesting read (depending on tastes), but here's the subsection: https://en.wikipedia.org/wiki/Pro-drop_language#English TLDR: yes, you can, in informal speech situations, otherwise rather not, as English is non-pro-drop.
I have never heard or read the words clitic or null in my lifetime. Lol. Even after being the reigning spelling bee champ each year from grades 2-7. Furthermore, while the roots of these words(?!) ring a bell, I haven't been familiarized with 'adverbially' nor 'syntactical,' either. Your intellect scares me and as such I opted to verbally assault said intelligence by sarcastically replying. My apologies. It was my first instinct to do this and I do not know how to delete previously posted measages.