Final answer:
Two sentences with misplaced modifiers are where the overdue status incorrectly modifies 'library' instead of 'book', and where 'the audience' is incorrectly suggested to have walked onto the stage.
Step-by-step explanation:
The two sentences that contain misplaced modifiers are:
- Bobby returned his library book to the library that was overdue.
- After walking onto the stage, the audience cheered loudly for the magician David Copperfield.
In the first sentence, it is not the library that was overdue, but the book. The correct sentence should be: "Bobby returned his overdue library book to the library." In the second sentence, it is implied that the audience walked onto the stage, which is not the case. The correct sentence should be: "After the magician David Copperfield walked onto the stage, the audience cheered loudly."