1. [of pears] was
2. [above the stage] work
3. [in the bleachers] is yelling
4. [near the shore] were damaged
Prepositional phrases specify a place or a kind of something. A prepositional phrase refers to any set of Preposition + Object or Preposition + Article (the, a, an) + Object that acts like a preposition. When choosing the correct form of the verb, refer back to the Subject of the sentence (in this case, Box, Lights, Fan, Buildings) to determine wether to use a singular or plural verb.
Hope this helps!