How to transform the following passive sentences into the active voice; remember that the subject of the passive is an object in the active. (Note: If the agent is missing, you will have to supply one to act as the subject for the sentences in the active voice.)

Example:The first American Nobel Prize was won by Theodore Roosevelt.

Changed:Theodore Roosevelt was the first American to win a Nobel Prize.

1.This year's cheerleading squad was chosen by a committee last spring.

2.The election of the class officers will be held on Tuesday.

3.Your car's oil should be changed on a regular basis.

4.The suspect is being kept in solitary confinement.