Answer:
a. He is as wise as his sister. (change into Negative)
⇒Neither he is wise nor his sister.
b. He put the cup on the shelf. (change into interrogative)
⇒Did he put the cup on the shelf?
c. He said to her. Will you play tomorrow? (change into indirect)
⇒He asked me that whether I play the next day.
d. Doctors cure patients. (Change into passive)
⇒Patients were cured by doctors.
e. She (not eat) yet. (Rewrite it using correct tense)
⇒she hadn't eaten yet.
f. Everybody has eaten..............? (use correct question tag)
⇒Everybody has eaten, haven't they?