Possunt sacroficare should work
in latin modal verbs always come after
Sacerdos uatesque should be ok, I think...
I did Sacerdos vatesque... and it was not accepted. (Does Duolingo Latin accept a u for a v in this spot as an alternate sometimes?)
They should accept
How do you find out the meaning of words you have not met before?
eg vates. This lesson leaves gaps.
Why not "...possunt sacrificare"?