Which sentence has a shift in its verb voice?

Question

The children were sure they could find the missing book, but their mother already knew where it was.
The building was built in 72 AD, but it was not built in one day.
She did not want to go, but everyone knew it was an important event.
He wanted to walk, but he was asked by his friend to take the bus.

Answer 1

The sentence that has a shift in its verb voice is:

He wanted to walk, but he was asked by his friend to take the bus.

In this sentence, "He wanted to walk" is in active voice, while "he was asked by his friend" is in passive voice. The other sentences maintain a consistent voice throughout.