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: Farmers, especially in developing countries, are often criticized for cutting down forests. But a new study suggests that many farmers recognize the value of keeping trees. Researchers using satellite images found at least ten percent tree cover on more than one billion hectares of farmland. That is almost half the farmland in the world. Earlier estimates were much lower but incomplete. The authors of the new study say it may still underestimate the true extent worldwide. The study found the most tree cover in South America. Next comes Africa south of the Sahara, followed by Southeast Asia. North Africa and West Asia have the least. The study found that climate conditions alone could not explain the amount of tree cover in different areas. Nor could the size of nearby populations, meaning people and trees can live together. There are areas with few trees but also few people, and areas with many trees and many people. The findings suggest that things like land rights, markets or government policies can influence tree planting and protection. Dennis Garrity, who heads the World Agroforestry Center, says farmers are acting on their own to protect and plant trees. The problem, he says, is that policy makers and planners have been slow to recognize this and to support such efforts. The satellite images may not show what the farmers are using the trees for, but trees provide nuts, fruit, wood and other products. They also help prevent soil loss and protect water supplies. Even under drought conditions, trees can often provide food and a way to earn money until the next growing season. Some trees act as natural fertilizers. They take nitrogen out of the air and put it in the soil. Scientists at the Center say the use of fertilizer trees can re-duce the need for chemical nitrogen by up to three-fourths. Trees also capture carbon dioxide, a gas linked to climate change. 
 Answer: there are more trees on farmlands than expected

Solution: Through the study, the researchers found that  _