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: Time Travel If you could travel in time, where would you go? Perhaps you would watch an original performance of a Shakespeare's play in Elizabethan England? What about hanging out with Laozi in the Spring and Autumn Period? Or maybe you'd voyage far ahead of the present day to see what the future holds. The possibility of time travel is indeed appealing. Stories exploring the subject have been around for hundreds of years. Perhaps the best known example is science fiction novel The Time Machine, which was written by H.G. Wells and published in 1895 for the first time. It was adapted into at least two feature films of the same name, as well as two television versions, and a large number of comic book adaptations. It is generally credited with the popularization of the concept of time travel using a vehicle that allows an operator to travel purposefully and selectively. The term "time machine", coined by Wells, is now universally used to refer to a vehicle transporting people into the far future. But could time travel actually be possible? Some scientists say yes, in theory. They propose using cracks in time and space called "wormholes", which could be used as shortcuts to other periods. Einstein's theory of relativity allows time travel in extreme circumstances. And British physicist Stephen Hawking says you could travel into the future with a really fast spaceship -- going at nearly the speed of light. Though building such a spaceship would of course be no simple task. Even if you could travel into the past, there is something called the "grandfather paradox". It asks what would happen if a time traveler were to go back in time and have his own grandfather killed for some reason, and therefore prevent himself from being born.If the time traveler wasn't born, how would he travel back in time? And would you really like to visit the future?In H.G.Wells' book, the main character travels into distant time where he arrives at a beach and is attacked by giant crabs. He then voyages 30 million years into the future where the only living thing is a black object with tentacles .If that's what's in store, maybe we are better just living in the present day after all.
Answer: suggest the possibility to invent the time machine
Solution: Einstein's and Hawking's theories _ .