Task: Question Generation
Input (English): Passage: On Christmas Eve in 19th-century London, Fred is sliding on ice on a sidewalk. He meets Peter and Tim Cratchit, sons of his uncle Ebenezer's clerk, Bob Cratchit. When Fred reveals who he is, the boys take off in terror. Fred soon arrives at the counting-house of his miserly maternal uncle, Ebenezer Scrooge. After declining an invitation from his nephew to dine with him on Christmas, Scrooge rejects two gentlemen collecting money for charity. That night, Scrooge reluctantly allows his employee Bob Cratchit to have Christmas off with pay but orders him back all the earlier the day after. Later Bob accidentally knocks off Scrooge's hat with a snowball. Scrooge dismisses Bob and withholds a week's pay to compensate for his ruined hat, also demanding a shilling to make up the difference. Bob spends the last of his wages on food for his family's Christmas dinner. 
In his house, Scrooge is confronted by the ghost of his deceased business partner, Jacob Marley, who warns Scrooge to repent his wicked ways or he will be condemned in the afterlife as Marley was. He tells Scrooge he will be haunted by three spirits.
At one o'clock, Scrooge is visited by the youthful Ghost of Christmas Past, who takes him back in time to his early life. Scrooge is shown his unhappiness when he was left to spend the holidays alone at school, and his joy when his sister, Fran, came to take him home for Christmas. The spirit reminds Scrooge that Fran, dead for some years, is the mother of his nephew. Scrooge is shown his early career in business and money lending as an employee under Fezziwig.
Output (English): Who explains that there will be three spirits?