(i) By way of using negative word with opposite adjectives, an affirmative
sentence could be transformed into negative sentence. As for examples:
Affirmative: Man is mortal.
Negative: Man is not immortal.
Affirmative: He is honest.
Negative: He is not dishonest.
Affirmative: I shall never forget you.
Negative: I shall always remember you.
Affirmative: No one can escape death.
Negative: All must submit to death.
Affirmative: Brutus loved Caesar.
Negative: Brutus did not hate Caesar.
Affirmative: Where there is fire, there is smoke.
Negative: There is no smoke without fire.
Affirmative: Everybody distrust a liar.
Negative: Nobody trust a liar.
(ii) By the way of changing degrees of comparison:
Affirmative: He is as good as I am.
Negative: I am not better than he is.
Affirmative: He is the best student.
Negative: No other student is as good as he.
Affirmative: As soon as the teacher arrived, the noise ceased.
Negative: No sooner dis the teacher arrive than the noise ceased.
(iii) There are also other ways to change a affirmative sentence to a negative sentence:
Affirmative: None but the brave deserves the fair.
Negative: Only the brave deserve the fair.
Affirmative: He is too weak to walk.
Negative: He is so weak that he cannot walk.