Translation:The child is between mom and dad.
As discussed elsewhere, in English the default is to assume that "mum and dad", with no ownership specified, implies the parents of the speaker. In Russian, it implies the parents of the person spoken about - so it is necessary to introduce the possessive pronoun to make the distinction.
The difference between definite and indefinite articles is pretty important actually ;)
"A child is between his mum and dad" isn't a common English form. It carries the meaning that any arbitrary child is to be found between his mom and dad. I do not think the Russian sentence has this meaning. ("There is a child between his mom and dad" would be more common, but then I think the default form of the Russian sentence would have been flipped around: "Между мамой и папой - мальчик.")
So.. it turns out.. as always.. my English knowledge is faulty... for I still see nothing wrong with what I wrote. I think that, since Russian has no articles, any sentence can be interpreted in both ways. Both that "the particular child" is found between it's parents at the moment - and that "any arbitrary child" is between it's parents.... I don't even see nothing wrong with the second option... Children are found between their parents xDD but maybe, as I said before, it's just that my English knowledge is faulty, so it doesn't sound strange to me... Thank you anyway :)
Just to be clear, by "any arbitrary child" I meant something like "all children," not simply an unidentified single child.
The sentence "A child is between his mum and dad" with standard intonation has the meaning that all children everywhere are between their respective mothers and fathers. The sentence is grammatical but certainly not common.
With pronunciation emphasis on "child" it means something like "It is a child that is between his mom and dad" (i.e. a child as opposed to perhaps a dog, or a canary, or an adult). It would also probably imply a certain degree of surprise about its being a child. This pronunciation actually seems a good deal more likely to me than with neutral intonation.
However, if there were additional context (as opposed to here where there's not), you can sort of get an indefinite article to take on definite meaning, so you certainly weren't wrong to wonder about the issue. An example:
"In this painting a boy is between his mom and dad." Because you know what painting you're talking about, "a boy" essentially means a certain, specific boy. The most obvious gradation in meaning between that and "In this painting the boy is between his mom and dad" is that in the later there can really only be one boy in the entire painting while in the former there might or might not be be another boy or boys that aren't between their parents. If this had been the sentence, I would definitely agree that Duo should accept either the indefinite or definite article version. But without that additional context, I think only accepting the definite article version makes sense since Duo largely confines itself to neutral structures and intonation patterns.
Yes, sure. In this case it has the same meaning. If you are interesting about the use "есть" in these sentences read the ns_shadow's comment:
In order to indicate a certain meaning, prepositions are used with a set grammatical case. Между and с/со (meaning "with), for example, always take the instrumental case. Мамы would be the genitive case, usually used to indicate some sort of possession. Learning which cases to use with which prepositions is absolutely a must, in addition to the meaning of course. Most dictionaries should list the appropriate case to use in each circumstance. Look here for an example of what I mean. https://en.wiktionary.org/wiki/%D1%81#Russian
A nice rundown of which preposition goes with which case can be found at https://en.wikipedia.org/wiki/Russian_grammar#Nouns.
oops! help needed! 'находится' to talk about a kid!? as far as i already knew, we use 'находится' to talk about terms that can't simply change their location like buildings or mountains but to talk about a kid!? is that seriously possible? anybody got the answer why!? please
"Находиться" (an infinitive for "находится") means "to be situated", "to be located", "to be" (in some cases), it's perfectly fine to use it for temporary locations or states. Here are a few examples:
If you can't find your friend in a big mall, for example, you can call them and say: Где ты находишься? Стой там, я сейчас подойду - Where are you right now? Stay there, I'll come in a moment.
Корабль находится в море - The ship is at sea
находиться в пути - to be on one's way, to be en route
находиться в тюрьме - to be behind bars, to be in jail
находиться в отпуске - to be on vacation
находиться под впечатлением - to be impressed [by smth].
находиться под влиянием - to be under the influence, to be influenced by
In British English, at least, 'mom (or 'mum') and dad' refers to the speaker's mother and father, not the subject's. Also, non-native English speakers should be aware that 'mum and dad', 'mummy and daddy' etc are informal expressions and should not usually be used in formal, written English.