This is an easy one, so try to do it in your head, without tabulating all the possible answers.

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Day-Nights and Night-Knights.

You are a sorcerer travelling by torch-light through the perpetual darkness of Agartha—the mythical subterranean world of Germanic legend. The magic spell that will transport you back to the Earth’s surface must be performed at night; however, owing to said perpetual darkness, it is impossible to tell whether it is night or day. In one of the sepulchres, you meet a knight on horseback.
‘Excuse me,’ you ask politely, ‘Is it true that the Knights of Agartha always know whether it is day or night? ’
‘True as the nose on your face!’ says the knight, drawing himself up.
‘Well, in that case, would you mind telling me whether...’
‘It is night!’ interrupts the knight. ‘But I feel it is my duty to add that Agartha is inhabited by two kinds of knights: The Day-Knights and Night-Knights. Day-Knights lie at night and speak the truth by day, and Night-Knights lie during the day and speak the truth at night.’
‘Oh, I see. And which are you?’
‘Bah! A Day-Knight, of course!’ says the knight angrily, and rides off at a trot into the darkness.
Will you perform your spell?

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Note: It is possible to determine from the knight's answers to your questions whether it is night or day and what kind of knight he was.