Sure! Here are the rewrites for each sentence:

1. Mai enjoys writing short stories when she has free time.
→ Mai is a writer of short stories in her free time.

2. Jill doesn’t run as fast as Tom.
→ Tom runs faster than Jill.

3. No one in the class is more intelligent than Peter.
→ Peter is the most intelligent student in the class.

4. When did your father start working in this factory?
→ How long has your father been working in this factory?

5. She is the most beautiful girl I have ever known.
→ I've never known anyone more beautiful than her.