PAGES of this book. The given sentence is in a passive voice form, hence we need to convert it into an active voice form.Find the subject (The pages of this book) and object (my baby sister) of the sentence and exchange their places. The given sentence is in the simple past tense. The active verb form for simple past is: Subject + V2 + object.So, 'were TORN' changes to 'tore'.At last line up the remaining PART. Following these steps, we finally get- My baby sister tore the pages of this book. Certain verbs are followed by certain prepositions. Some of them are given below:vexed at, surprise/astonished/amazed at, known to, tired of, engulfed in, etc.Example:His weird behaviour SURPRISED me. (active)I was surprised at his weird behavior. (passive)