Word Negation

Negative sentences can be made either by negating the entire sentence or by negating a word. When making a negative sentence by negating a word, 이다 is changed to 아니다, 있다 is changed to 없다 and 알다 is changed to 모르다. Of these, 아니다 is written in the form 이/가 아니다, but when used in the spoken form, 이/가 is often omitted.