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 professor stopped the scientists .
The scientists stopped the professor .

The student contacted the artist who the tourists recommended .
The artist contacted the tourists .

The judge by the students advised the doctors .

The doctors advised the judge .