Question

Kevin built his science fair project in the laboratory. In which of the following has the sentence’s verb been changed to the passive voice? Kevin’s science fair project contains materials from the laboratory. In the laboratory, Kevin built his science fair project. Kevin’s science fair project was built in the laboratory.

Answer 1

The sentence that contains a verb which has been changed to the passive voice is Kevin’s science fair project was built in the laboratory. Passive form of the verb is when the subject undergoes the action of the verb, the example to remember this simple rule is: "something is done by someone". In this case we have 'the project was built (by Kevin)' while the rest of options contain different interpretations of active form.

Answer 2

It might be said that the correct option in passive voice is Kevin´s science fair project was built in the laboratory.
The active sentence was Kevin built his science fair project in the laboratory so the project and its adjectives are in the passive the subject of the sentence and the verb "build" is transformed into the passive by adding the verb to be. In this case, as the active sentence is in the past, we use the verb to be in the past as well. so you get "was built".