Yep, it's a real 26-letter sentence, using each letter only once!
If I knew the sentences, it would be a world of difference (and I think after like 20 times you would.) I have heard about the fox one, but do not know it exactly, same goes for; something with chickens and a basket and pudding and proof. So even though those ring a bell, I will still need to look up for almost every word ( I do know that "the" comes after "in" for example with the pudding sentence..)
Im good though, dont feel the urge to try more.