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That is the most difficult part on learning Korean.
~가 usually can be placed after the vowel "ㅐ ㅔ and ㅣ"
and make the noun subject of the sentence.
내가(I ~), 너희가(You ~ ,-plural) , 네가(You~ , singular)
저거 means "That is~/That would...
저 meand 1. "I" 저는 키가 작습니다. - I am rather short.
You can use 저 in this case show your respect to the listener.
저 - that
저기 있는 ~ there is something ~
저것은 /저거~ that is~
You know exact usages in Korean, great!
