The Subject Particle 가 and 이
The subject particle is added to a word to indicate that it is the subject of a clause. 가 is added to a noun ending in vowel and 이 is added to a noun ending in a consonant.
If the predicate at the end of the clause is a verb the subject is the executor of the verb.
, .Teenagers drink and smoke.
If the predicate at the end of the clause is an adjective, the adjective describes the subject.
민준 .Minju used up all his pocket money and walked home from school.