Step 1: Understanding the Concept:
When converting a sentence to passive voice, the object becomes the subject. While "by" is the most common preposition, specific verbs take different prepositions. Step 2: Detailed Explanation:
1. Subject: My school bag; Verb: contains; Object: ten books.
2. Passive construction: Object (Ten books) + helping verb (are) + V3 (contained) + Preposition + Subject.
3. The verb "contain" is always followed by the preposition "in" in its passive form, not "by". Step 3: Final Answer:
The correct sentence is: "Ten books are contained in my school bag."