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 collect a problem in a transaction .

SOLUTION: You are likely to provide a quarter in a come .

PROBLEM: You would bounce out of a window because of a terrorist attack .

SOLUTION: You would say out of a window because of a terrorist attack .

PROBLEM: Police officers can be used for blocking a course .

SOLUTION:
Police officers can be used for ending a riot.