Given the task definition, example input & output, solve the new input case.
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
Output: Researchers did experiments on kids in order to find out _ .
It is clearly mentioned in the article that to the check effect of mood on children is the main purpose of the experiment.

New input case for you: Article: An early invention by Albert Einstein has been rebuilt by scientists at Oxford University. They are trying to develop an environmentally friendly refrigerator that runs without electricity. We all know that modern fridges cause damage to the environment. They work by using a kind of man-made greenhouse gas called Freon , which is far more damaging than carbon dioxide. Now Malcolm McCulloch, an electrical engineer at Oxford, is leading a three-year project to develop appliances that can be used in places without electricity. His team has completed a prototype of a fridge patented in 1930 by Einstein. It used only pressurized gases to keep things cold. The design was partly used in the first refrigerators, but the technology was dropped when more efficient compressors became popular in the 1950s. That meant a switch to using Freon. Einstein's idea uses butane and water and takes advantage of the fact that liquids boil at lower temperatures, when the air pressure around them is lower. "If you go to the top of Mount Qomolangma, water boils at a much lower temperature than it does when you're at sea level and that's because the pressure is much lower up there," said McCulloch.At one side is the evaporator , a bottle that contains liquid butane. "If you introduce a new vapor above the butane, the liquid boiling temperature decreases and, as it boils off, it takes energy from the surroundings to do so," says McCulloch. "That's what makes it cold." The gas fridges based on Einstein's design were replaced by Freon-compressor fridges partly because Einstein's design was not very efficient. But McCulloch thinks that by changing the design and replacing the types of gases used it will be possible to quadruple the efficiency. However, McCulloch's fridge is still in its early stages. "It's very much a prototype," he said. "Give us another month and we'll have it working."
Answer: is being redesigned because it could be used in places without electricity
Output:
According to the passage, an early invention by Albert Einstein _ .