Explanation:

Find clauses in this sentence and state their kinds e.g. Adverb , Adjective or Noun .

She has won many prizes when she was in school .

ans- adjective clause "when she was in school .

Change it into Passive Voice

ans- Many prizes have been won by her when she was in school.

Change the Clauses in this sentence to phrase

ans- When She in school she was many prized winner.