In this task, we ask you to elaborate the sentence without changing its general meaning. You can do so by explaining further the input sentence, using more precise wording, adding qualifiers and auxiliary information etc.
Q: In grammar , case shows the job of a noun , adjective or pronoun in a sentence .
A: 
Case is a special grammatical category of a noun , pronoun , adjective , participle or numeral whose value reflects the grammatical function performed by that word in a phrase , clause or sentence .