"Paila ke keiki kāne i ka naʻaukake."

Translation: The boy boils the sausage.

[SamOhuGon]

"The boy is boiling the sausage" should also be accepted.
Although Ke paila nei would give more immediacy, in normal conversation the implication would be that the boy is boiling the sausage, rather than the boy boils the sausage (e.g., as a normal chore)

[KarinLynn1]

good to know (thx for comment) - but as a neophyte if I had said "is boiling" and it was marked correct, I wouldn't have caught the nuance that it really is plain old present tense without the "nei."