In this task, you are given a premise sentence. Your task is to write a new sentence by substituting the subject and object (i.e., the input's subject should be output's object and vice versa.). The generated sentence must be fluent and shouldn't change the voice (i.e., passive or active) of the input.

The artist that the actor stopped avoided the professors .
The professors avoided the actor .

The president helped the secretary .
The secretary helped the president .

The artist in front of the president introduced the scientists .

The president introduced the artist .