maybe he should tell the truth. haha just kidding I know it meant the body position.
Well, 1000% of the feminine nouns ending in -ь take -и in the Prepositional.
Should "The boy lies on the bed" be an accepted translation? Does the Russian sentence differentiate between "A boy" and "The boy"?
"New" information is typically at the end of the sentence. Here, we're familiar with the bed, implying we don't know who the boy is, so "a" boy.
Why "Мальчик лежит на кровати" is not accepted. Is this a wrong sentence order in Russian in general?
The English "A boy is on the bed" is a more bookish way to say "There is a boy on the bed", which, actually, is quite different from "The boy is on the bed", which is the most likely interpretation of your translation.
The boy is lying on a bed is cobsidered wrong... Hmm, even gramatically so? Or more a convention, the notion that the boy is at the end, new info, so therefore he is LIKELY the unknown one? What about "The boy is lying on THE bed"? Will this be accepted... (I am quite confounded at this juncture)...
Preposition and the most vital information at the end. thus it complete the analyses. The rest of the notes are just wasting the time