TASK DEFINITION: Given a sentence, generate a new sentence by performing small changes on the sentence. Here, make sure that the changes are semantically related and syntactically similar to the input. And the generated sentence should have high commonsense plausibility, that is to have reasonable probability of it being true.
PROBLEM: You are likely to knock a couple in the grass .

SOLUTION: You are likely to enter a lake in the grass .

PROBLEM: You can accept or vary the lyrics of a song .

SOLUTION: You can audio or read the lyrics of a song .

PROBLEM: If you apply to pay by credit card then you should put credit card .

SOLUTION:
If you want to pay by credit card then you should combine credit card .