Generally "an" or "na" is needed. It's like you're saying "you like the food there".
"These things" could be translated as "Na rudaí seo",
"Those things" could be translated as "Na rudaí sin",
"This thing" could be translated as "An rud seo", and
"That thing" could be translated as "An rud sin".
When Google Translate conflicts with just about any other source, it's a safe bet that Google Translate is wrong. The general rule is that if you think you need to use Google Translate for Irish, you don't know enough Irish to understand the mistakes that is is making on your behalf.
sin can mean "that" in some circumstances, (sin é - "that's it", mar sin - "like that") but to say "that X" you need the an - an X sin.
ann can mean "in it" and it can mean "there", an it can mean other things too. Ansin can mean "there" and "then".
To be honest, I'd be hesitant to give you any always rules, I sort of have to say it to myself a few times and see does it '''feel''' correct. I'm not a native speaker, I learnt Irish in school some years ago, so I'm not a definitive source of rules. I'm just trying to help out here where I can, because I am so happy and greatful for this course and all the work put in by the team, and I want to do my small bit to help Irish.
Anyway, having gone through a few examples in my head, I '''think''' so. Anything like "is maith liom X sin" just sounds wrong without a definite article. "Is maith liom cailíní sin" sounds more like "I like girls there", as opposed to "is maith liom na cailíní sin = I like those girls there". But I'll ask someone to varify that for me.
No. You would have to either use the question version of the copula (an), or add some extra phrase at the end to indicate that it is a question:
- An maith leat an bia sin? Do you like that food?
- Is maith leat an bia sin, nach ea? You like that food, don't you? (literally You like that food, isn't it?)