TASK DEFINITION: You will be given two sentences. One of them is created by paraphrasing the original one, with changes on an aspect, or using synonyms. Your task is to decide what is the difference between two sentences. Types of change are explained below:
 Tense: The verbs in the sentence are changed in tense.
Number: Plural nouns, verbs and pronouns are changed into single ones or the other way around.
Voice: If the verbs are in active voice, they're changed to passive or the other way around.
Adverb: The paraphrase has one adverb or more than the original sentence.
Gender: The paraphrase differs from the original sentence in the gender of the names and pronouns.
Synonym: Some words or phrases of the original sentence are replaced with synonym words or phrases. Changes in the names of people are also considered a synonym change. Classify your answers into Tense, Number, Voice, Adverb, Gender, and Synonym.
PROBLEM: original sentence: George got free tickets to the play , but he gave them to Eric , because he was not particularly eager to see it . paraphrase: Lily got free tickets to the play , but she gave them to Joan , because she was not particularly eager to see it .

SOLUTION: Gender

PROBLEM: original sentence: John was doing research in the library when he heard a man humming and whistling . He was very annoying . paraphrase: John and Steve were doing research in the library when they heard men humming and whistling . They were very annoying .

SOLUTION: Number

PROBLEM: original sentence: Jane knocked on Susan's door , but there was no answer . She was disappointed . paraphrase: Susan's door was knocked on by Jane , but there was no answer . She was disappointed .

SOLUTION:
Voice