A question that is free of any grammatical or logcal errors, should be labeled 'yes', otherwise it should be indicated as 'no'. A question is grammatically correct if all its entities i.e. nouns, verbs, adjectives, prepositions, pronouns, adverbs are at appropriate position. A question is logically correct if the semantic makes sense.

Example Input: Sentence: A thwarted Mongol invasion in 1274 weakened the Kamakura regime. 
Question: Is the invasion still taking place today?
Example Output: Yes.

Example Input: Sentence: Then they laid down on some towels and enjoyed the sun. 
Question: How long did they enjoy under the sun?
Example Output: No.

Example Input: Sentence: Durer's father died in 1502, and his mother died in 1513. 
Question: Was Durer alive when his mother died?
Example Output:
Yes.

