Yes it is!
Why does "A vida é dura" translate as "Life is hard," while "O trabalho é duro" doesn't translate as "Work is hard"? I typed that and it said the correct answer was "The work is hard." I don't see the difference between these two constructions.
I would imagine that both "Work is hard" and "The work is hard" should have been accepted, but Duo just didn't have "Work is hard" in their database yet.
Could it be "life is tough"?