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.
Example: 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
Example solution: Researchers did experiments on kids in order to find out _ .
Example explanation: It is clearly mentioned in the article that to the check effect of mood on children is the main purpose of the experiment.

Problem: Article: Several different stories are told about the origin of Saint Valentine's Day. One legend  dates as far back as the days of  Roman Empire . According to the story, Claudius, the Emperor of Rome, wanted to increase the size of the army. He knew that it would be easier to get young men who were not married to join the army. Therefore, he made a rule that no young men could marry until he had served in the army for a certain number of years. A priest  named Valentine broke the rule and secretly married a great number of young people. Finally, Claudius found out about Valentine and put the priest in prison, where he remained until his death on February 14.     After his death, Valentine was made a saint  and the day of his death was named Saint Valentine's Day. It became the custom for lovers to send each other message on this day. Now Saint Valentine's Day is a time for people to send one another their greeting of many kinds.  February 14, Valentine's Day, is sweetheart's day, on which people in love with each other express their tender emotions .     People sometimes put their love message in a heart-shaped box of chocolates or a bunch of flowers tied with red ribbons . Words of letters may be written on the flower-covered card, or something else. Whatever the form may be, the message is almost the same "Will you be my Valentine?" 
 Answer: young men could get married if they had served the army for a number of years.

Solution: According to the rule,   _  .