You will be given a definition of a task first, then an example. Follow the example to solve a new instance of the task.
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: John, a famous musician, took his priceless antique violin and played it in the crowded subway station. The music from the violin was delicately streaming throughout the whole station. However, during the one-hour play, only six or seven people were truly appreciating the charming music. A three-year-old kid was so fascinated by the music that he forgot everything around. John only got 52 dollars for his work that day. However, in normal days, when John is about to hold a concert, one ticket can be sold at more than 100 dollars and it is extremely hard to buy a ticket even at such a high price. Therefore, later, many passers-by in the station that day felt deeply regretful for not recognizing the famous musician and missing such a valuable but cheap music feast. I have a very busy friend who had totally changed after knowing that his wife came down with incurable illness. He cooked by himself for the family and took a walk with his wife every day. Nonetheless, his wife still did not manage to conquer the illness and passed away after three months. After that, he often sighed miserably that due to his past busy life, he had missed a lot of beautiful time with his wife. But now, it is impossible to make up for it. It is no use crying over spilt milk. We have missed a lot of precious things in our life without knowing to cherish them. Actually, I also missed something precious before. The reason why we would have missed those precious things is less than simple: we had thought that we could still own them tomorrow. Nevertheless, tomorrow is actually by no means reliable. There was a famous Buddhist monk saying that in many people's lives, they have only done two things: _ The result is that they were always too late to cherish what they had before they lost it. We would often claim to do something when we grow up, or when we have money or when we become old, etc. However, when we reach the condition we have expected, we could no longer realize our wish, because we have lost it by then.
Answer: they are too careless to cherish precious things
Solution:
The reason why people often regret may be that _ .