Hello there,
I've read many definition about <em>이,가 / 은,는 </em>and I've thought that I can clearly understand it untill I learned this one:
오늘이 무슨 요일이에요?
오늘은 금요일이에요.
이것은 무엇입니까? =
이게 뭐예요? =
이것이 뭐예요?
Is that means any questions use 이,가, then answers use 은,는?
Could you please let me know the difference or how to use 이,가 / 은,는 correctly?
Thanks for your concern,
이 가 are the same, used for subject of sentence. The only difference is the ending character of the word * 내가, 책이, 기차가, 강이, if the word ends in vowel, then 가, if the words in consanant, then 이
은, 는 follow similar rule, based on ending character of the word.
In terms of used, it is used for distinguishing, contrasting. Japanese and Chinese both have a similar strucuture, Japanese "ga", and Mandarin "de" which I just learned.
A basic statement would not used
basic - "today is wednesday" 오늘 (this word acutally does not take the 이 가 particle, since it's a time)
contrast/distinguish - "today the weather is really bad (compared to yesterday)" 오늘은