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.
One example is below.
Q: 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
A: Researchers did experiments on kids in order to find out _ .
Rationale: It is clearly mentioned in the article that to the check effect of mood on children is the main purpose of the experiment.
Q: Article: Runners in a relay  race pass a stick in one direction. However, merchants passed silk, gold, fruit, and glass along the Silk Road in more than one direction. They earned their living by traveling the famous Silk Road. The Silk Road was not a simple trading network. It passed through thousands of citied and towns. It started from eastern China, across Central Asia and the Middle East, and ended in the Mediterranean Sea. It was used from about 200 B, C, to about A, D, 1300, when sea travel offered new routes  , It was sometimes called the world's longest highway. However, the Silk Road was made up of many routes, not one smooth path. They passed through what are now 18 countries. The routes crossed mountains and deserts and had many dangers of hot sun, deep snow and even battles. Only experienced traders could return safe. The Silk Road got its name from its most prized product. Silk could be used like money to pay taxes or buy goods. But the traders carried more than just silk. Gold, silver, and glass from Europe were much found in the Middle East and Asia. Horses traded from other areas changed farming practices in China. Indian merchants traded salt and other valuable goods. Chinese merchants traded paper, which produced an immediate effect on the West. Apples traveled from central Asia to Rome. The Chinese had learned to graft  different trees together to make new kinds of fruit. They passed this science on to others, including the Romans. The Romans used grafting to grow the apple. Trading along the Silk Road led to world-wide business 2,000 years before the World Wide Web. The people along the Silk Road did not share just goods. They also shared their beliefs. The Silk Road provided pathways for learning, diplomacy , and religion 
 Answer: to deal with a lot of difficulties
A:
It's probable that traders along the Silk Road needed  _  .