"The girls are sleeping."
I had a question right before this one that was "Where are the girls?", and the correct answer was "Ubi sunt puellae". However, on this one, i put "Puellae sunt dormiunt", and got it wrong, it wanted me to leave out 'sunt'. Why is "sunt" needed on the other question, but they want it left out here?
'They are sleeping' is a form of the present progressive in English, compare to the simple present 'They sleep' and the emphatic present 'They do sleep'. All three can be translated into Latin as dormiunt since Latin does not make the same differentiation as English (more reliance on context than difference in verb form). Puellae sunt dormiunt would be similar to saying in English 'the girls are are sleeping' or 'the girls are sleep'.