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: A snowball is used to defend oneself against an alert .

SOLUTION: A chain is used to store oneself against an attack .

PROBLEM: You would go to a session because it is a social spot .

SOLUTION: You would see to a standard because it is a social event .

PROBLEM: You would play the piano because it has a beautiful sound.

SOLUTION:
You would open the piano because it has a beautiful history .