Hi

All noun comes after حرف جر should takes KASRA

< حروف الجر < من إلى عن على في ب ل حتى

but the is another noun doesn't take KASRA it's named الممنوع من الصرف

example

من سليمانَ
الى عمرَ 

في مساجدَ

yes thats right, you should study grammer (e3rab) to know when we put dama/fatha/kasra, it has rules in general ^_^

Yes, that's right I forgot to say that, الممنوع من الصرف doesn't take the kasrah as kamel said :)
Osamah, I don't undersatand your question ^_^

NO no no Osama ^_^ , the example you say is wrong as it actually follow the law after the preposions the word will be with kasrah
so in your example you should say, َأنت تعيش في بــَـيــْـتــِك
as in e3rab : في .. حرف جر
بيتك ..بيت = اسم مجرور بفي و علامة جره الكسرة
ك=ضمير مبني في محل جر مضاف إليه
so we pronounce the pronoun ك with fatha, but give it e3rab with kasrah as it is مضاف إليه that's why we say مبني :)

Thanks for the response. I ask this question year ago and now your answers are making sense to me.