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In this task, you're given an article and an answer. Your task is to generate the fill-in-the-blank question for this answer based on the given article. The blanks are always at the end of the question, and can be filled with more than one word or phrase.

Article: Homework can put you in a badmood , and that might actually be a good thing. Researchers from the University of Plymouth in England doubted whether mood might affect the way kids learn. To find out the answer, they did two experiments with children. The first experiment tested 30 kids. Someshapes were hidden inside a different, larger picture. The kids had to find the small shapes while sitting in a room with either cheerful or sad music playing in the background. To test their mood, the scientists asked the kids to point to one of five faces, from happy to sad. Children who listened to cheerful music tended to point to the smiley faces while the others pointed to the unhappy ones. The researchers found that sad kids took at least a second less to find the small shapes. They also found an average of three or four more shapes. In the second experiment, 61 children watched one of two scenes from a film. One scene was happy, and the other was sad. Just like in the first experiment, kids who saw the sad scene acted better compared to the others. The researchers guessed that feeling down makes people more likely to focus on a problem or difficult situation. Not all scientists agree with them, however. Other studies argued that maybe, that cheerful music in the first experiment distracted kids from finding shapes. While scientists work on finding out the answers, it still might be wise to choose when to do your tasks according to your mood. After eating a delicious ice cream, for example, write an essay.
Answer: whether mood affects their learning ability
Solution: Researchers did experiments on kids in order to find out _ .
Why? It is clearly mentioned in the article that to the check effect of mood on children is the main purpose of the experiment.

New input: Article: Adults usually do not remember most of the things that are taught by their teachers at school. But this story is one such lesson that I will never forget. Every time I drift off course, I think of this story. It was a normal Monday morning, and my teacher was teaching us on important things in life and about devoting ourselves to what is important to us. This is how the story went: An old man lived in a certain part of London, and he would wake up every morning and go to the subway. He would get onto the train right to Central London, and then sit at the street corner and beg. He would do this every single day of his life. He sat at the same street corner and begged for almost 20 years. His house was dirty, and a stench came out of the house and it smelled terrible. The neighbors could not stand the smell any more, so they called for the police officers to clear the place. The officers knocked down the door and cleaned the house. There were small bags of money all over the house that he had collected over the years. The police counted the money, and they soon realized that the old man was a millionaire . They waited outside his house expecting to share the good news with him. When the old man arrived home that evening, one of the officers told him that there was no need for him to beg any more as he was a rich man now, a millionaire. But the old man said nothing at all; he went into his house and locked the door. The next morning he woke up as usual, went to the subway, sat at the street corner and continued to beg. Clearly, this old man had no great plans, dreams or anything significant for his life. We learn nothing from this story other than staying focused on the things we enjoy doing.
Answer: they couldn't bear the smell from the old man's house
Solution:
The neighbor called the police because _ .