1: Express State Of Being

Question 1

What are the conjugation rules for the negative state-of-being?

Answer 1

Attach 「じゃない」 to the noun or na-adjective

Question 2

What are the conjugation rules for the past state-of-being?

Answer 2

Attach 「だった」 to the noun or na-adjective

Question 3

What are the conjugation rules for the negative past state-of-being?

Answer 3

Conjugate the noun or na-adjective to the negative first and then replace the 「い」 of 「じゃない」 with 「かった」
Example: 友達じゃない → 友達じゃなかった＝友達じゃなかった

Question 4

How do you declare that something is so?

Answer 4

Attach 「だ」 to the noun or na-adjective