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 doctors introduced the bankers .
The bankers introduced the doctors .

The students recognized the presidents .
The presidents recognized the students .

The professors who the artist contacted called the athletes .

The artist called the professors .