"Dívala se na tetina ústa."

Translation: She was watching her aunt's mouth.

[BjrnMrtens]

According to a Czech native friend, it's not clear who's aunt she is watching, so I think "She was watching aunt's mouth." should also be accepted?

[BoneheadBass]

That sounds very odd in English without an article or possessive. "An aunt's mouth" and "the aunt's mouth" don't work either. Options with other possessives, however, also are accepted.

[BjrnMrtens]

Makes sense! I'm learning a fair amount of English in addition to Czech here :)

[Chris545852]

Why not "she looked at her aunts mouth"?

[VladaFu]

She looked is a single action, we translate that with podívala se (perfective).