Give the rules to change positive sentences into negative sentences

Give the rules to change positive sentences into negative sentences 302 (2' He is as greedy as Midas. (3' I t•ope I shall succeed this year. (4 As soon as the beast felt thirsty, he proceeded (5' Allis well that ends well. (6' m Johnson declined Lord Chesterfield's offer. (7) Mumbai is the richest city in India. (8' Everyone will admit he is honest. He was a boy of marked intelligence. (10' You will miss the train unless you run quickly. (11) It is too difficult for a man to do it single handed (12) Even Matriculates can apply for this job. (13) This fact is too evident to require proof. (14) All men are mortal. (15) He disbelieves my story. (16) He refused to divulge the secret. (17) She alone believed him. (18) The new officer is unpopular with his subordin (19) Her piety was beyond doubt. (20) The servant's faults were unforgivable;. (21) It always pours when it rains.

Dear student,
There are no specific rules to change an affirmative sentence into negative and vice versa. However, there are certain rules to attempt the grammar topic "Transformation of sentences" as it mandates that you perform such conversion without changing the meaning.

For example: 

Brutus loved Caesar. (affirmative)

Brutus was not without love for Caesar. (negative)

Some rules to covert an affirmative sentence to negative are given below for your reference:

1.  Sometimes → Replaced by → Not + always.

 Affirmative: Radha sometimes visits me.

 Negative: Radha doesn’t always visit me.

2. As soon as → Replaced by → No sooner had ----- Than

Affirmative: As soon as the child saw the police, he ran away.

 Negative: No sooner had the child seen the police that he ran away.

3. Only→ Replaced by → None but

 Affirmative: Only God can help us.

 Negative: None but God can help us.

4.  Both----and → Replaced by → not only ---- but also.

Affirmative: Both Divya and Dipika were excited.

Negative: Not only Divya but also Dipika was excited.

Regards.