e.g Casual: どの　いえが　あなたの？ Plain: どの　いえが　あなたのか？ Polite: どの　いえが　あなたのですか？

Hello Davidさん When の no is placed at the end of a statement, it often indicates that the statement is intended to explain something or to provide information. This is の no’s function, as an explanation particle. It is only used when speaking casually. （In the writing form would be + ですか？） ●デイビッドさんは忙（いそが）しいの？（could add ですか？in the end） Is David-san busy ? if becomes English there is no difference both デイビッドさんはいそがしいですか？andデイビットさんはいそがしいのですか？　but the sentence with の has more weight on the state not the subject. ●デイビットさんは日本語を勉強しているの？ ●ピザが好きなの？ I am just a native Japanese speaker but I hope that helps a little :) also, you have been studying a lot !!! I'm so impressed how often made those questions on here and that shows you've been working so hard !!! とても　素敵（すてき）です🌸