I used the word 'forever' and it's only "almost" correct. What's the problem?
It is just that 'forever' is not yet in the list of valid answers. Duo will add it shortly.
British English seems to use both 'forever' and 'for ever', despite concerns as recently as the seventeenth century about the validity of the single word version:
""Forever; ’tis a single word! Our rude forefathers deem’d it two: Can you imagine so absurd A view?
Forever! What abysms of woe The word reveals, what frenzy, what Despair! For ever (printed so) Did not."
(Charles Stuart Calverley, C18th poet and wit)