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: BUNOL, Spain (AFP) -- Tens of thousands of people from around the world threw tons of ripe tomatoes at each other in an annual food fight that painted the eastern Spanish town of Bunol red. More than 40,000 people, including many visitors from Australia, Britain and the United States, took part in the food fight known as the "Tomatina", now in its 64th year, a spokeswoman for Bunol's town hall said. They were provided with over 100 tons of tomatoes by the town council for the battle which lasted about one hour and left participants covered in red. Many men were shirtless while others wore old clothes, hardhats, goggles or protective plastic sheets. Shopkeepers put up huge plastic covers on their store fronts or boarded them up to protect their properties from the sea of red mush . After the battle, governmental workers and local residents used "giant hoses" to clear the walls and streets of the tomato pulp in just half an hour while the participants headed to a nearby river where temporary showers were set up. The event cost the town of some l0, 000 residents 40,000 dollars, and Spanish media reported. The "Tomatina" is held each year in Bunol, located in a fertile region about 40 kilometers north of the coastal city of Valencia, Spain's third-largest city, on the last Wednesday in August. The origins of the event are unclear although it is thought to have its roots in a food fight between childhood friends in the mid-1940s in the city. It has grown in size as international press coverage brought more and more people to the festival.
Answer: kept their store fronts covered
Answer:
To keep their stores safe, the shopkeepers _ .