instruction:
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.
question:
The secretaries mentioned the athlete who stopped the scientists .
answer:
The scientists mentioned the secretaries .


question:
The secretaries stopped the presidents .
answer:
The presidents stopped the secretaries .


question:
The presidents helped the professor behind the doctor .
answer:

The professor helped the presidents .