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 find a football stash in an envelope .

SOLUTION: You are sorry to find a th parcel in an envelope .

PROBLEM: You are likely to found a clip in a transcript .

SOLUTION: You are likely to generate a clip in a C .

PROBLEM: You are likely to find a pin in a tree .

SOLUTION:
You are likely to find a grape in a tree.