I wish I was born in London. ای کاش در لندن به دنیا می‌آمدم (Formal) ای کاش لندن به دنیا می‌اومدم (Informal) I wish You knew. ای کاش می‌دانستید (Formal) ای کاش می‌دونستی (Informal) I wish I had a car. ای کاش یک ماشین داشتم (Formal) ای کاش یه ماشین داشتم (Informal) Alternatively, You can omit the word "ای" from the beginning of the sentences. Hope this helps ;)

"kaash" isn't used only for unachievable wishes, it may be used for ordinary wishing as well: kaash baaroon bebaare. کاش بارون بباره kaash zoodtar ye taxi biaad. کاش زودتر یه تاکسی بیاد kaashki betoonam khoob dars bekhoonam taa qabool sham. کاشکی بتونم خوب درس بخونم تا قبول شم kaashki marizit zood bartaraf she. کاشکی مریضیت زودتر برطرف شه "kaashki" may be used instead of "kaash" informally with identical meaning.

Hey,When a person wants something but is not prepared to put in any effort to obtain it. "kash" we use it for bad and good situation,when we couldn't do it and that is impossible or unattainable situation...well,let me to say a couple examples I wish I had some money I wish to travel. I wish that it were morning. We wish you a Merry Christmas. Good luck

kash baraye arezooi k fekr mikoni mahale, ya baraye hasrat khordane karhaei ke dar gozashte mitunesti anjam bedi be kar mire kash behesh gofte budam dusesh daram kash madaram zende bud kash man betunam ghahreman besham

Kash = wish Kash estefadeh mishavad bray vaziyatiy ke arzo mikoneed atefagh bioftad Desire to happen something