If it is posed as a question, then there needs to be an interrogative associated with the sentence. In English we do a great deal with vocal tone, but our Esperanto brethren who natively speak a tonal language will, pretty much always, miss many of those cues. So: "He can't accept the truth?" will still need to be something akin to "Ĉu li ne povas akcepti la veron?" or "Li ne povas akcepti la veron, ĉu?"
And that's the truth bpbpbpbpt!