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.

Let me give you an 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
The answer to this example can be: Researchers did experiments on kids in order to find out _ .
Here is why: It is clearly mentioned in the article that to the check effect of mood on children is the main purpose of the experiment.

OK. solve this:
Article: There was a huge battle between the warriors of Greece and the people of Troy. Prince Paris from Troy had stolen away the Greek queen; Helen. The Greek warriors set sail for Troy to fight for their queen. The battle outside Troy lasted for ten years. The men were fed up and wanted to return to their homes. Athene, goddess of war gave Ulysses the idea for a plan to end the war. They built a big wooden horse which they put in the middle of their encampment . Next they pretended to give up their camp. In reality many soldiers hid inside the wooden horse. Once they thought the camp had been abandoned the Trojans went out to check. They needed to know if the war was really over. They walked through the abandoned encampment and eventually found the wooden horse. They could not decide what it was. Some wanted to take it into the city, others thought that it was a gift to Zeus and feared touching or moving it in case they upset Zeus. Some Trojans decided to take it back into the city. They called a large group of troops, attached ropes and pulled it into the city. A huge celebration started. The city was free from war for the first time in nine years. Everybody feasted, drank and danced until eventually the merriment was over and they all went to sleep. This was the moment that the wooden horse opened a big flap hidden underneath. Out crept Ulysses and all of his men. They killed the sleeping troops, rescued Queen Helen, met up with the rest of their army and set sail for home. The story of the return journey is told in The Odyssey, a collection of poems piecing together the bits of the story from the many different places where the story took place.
Answer: the Greek warriors fought against Troy for their queen stolen away
Answer:
Greece and the people of Troy were at war because _ .