well for the "ghain" it sounds like when u r using a gargle :D or gargle with water if u dont have a "mouthwasher solution" , then mmmmm try to gargle without water lol so u will be pronouncing it ;) hope this can help

it's like in french the letter (r) for example : RegaRder

hey!! thank u so much for ur "pdonunciation" i think i can voice out the word rrrrrRussia now LOL thanks n I'll try harder !

i have a trick i got in the past from my teacher, maybe it helps you. the problem is, that i believe you're chinese, right? so you don't know to pronounce this letter anyway but that's no problem at all, so let's try over english....this language also includes the letter "r", just a second pronunciation. so now, you imagine (and this is for "rrrr" :D) : take a word‎ with "r", maybe "pronunciation". then you change the "r" into a "d". then you have "pdonunciation". try to speak it. first slow, then faster. just try it, it must not be perfect, because it'S just a help. so you say "pdonunciation pdonunciation, pdonunciation..." and you try to get faster and try to let the "d" swing fast over the peak of your tongue. and say it loud of course. then soon you get the "ra" or "rrrr" :D. with ghain - i don't know if i can help you. i am german and in that language ghain is just "r"....well...maybe you know the name "khaled"? the ghain is just like "kh" just softer or with less energy when spoken, do you understand me? so just say "kh" with less energy or less air. hope i could help you :)