can you give me the rules for transformation of sentences?

Dear student, 

Under the topic of transformation of sentences:

1. Interrogative sentences can never be changed to imperative form; 

2. Negative sentences can be changed to assertive form in the following way: a) The news is so good that it can not be true changes to The news is too good to be true. 

3. Passive to active instances are: - He was asked by the principal to leave; - The house was bought by them.- The orange was peeled by my mom.