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.

Article: A machine which makes water out of air could become the greatest household invention since the microwave. Using the same technology as a dehumidifier , the Water Mill is able to create a ready supply of drinking water by getting it from a limitless source-the air. The company behind the machine says not only does it offer all alterative to bottled water in developed countries,but it is a solution for the millions who face a daily water shortage. The machine works by drawing in damp air through a filter and over a cooling element which changes it into water droplets.It can produce up to 12 liters a day.The Water Mill will also produce more water when storms pass over, as the humidity in the air increases.In keeping with its ecodevelopment,the machine uses the same amount of electricity as three light bulbs. Inventor Jonathan Ritchey said:"The demand for water is .People are looking for freedom from water distribution systems that are shaky and unreliable". The machine,which is about 3 feet wide,is likely to costPS800 when it goes on sale here in the spring.Its maker, Canadian firm Element Four, estimates that a liter of water will cost around 20 pence to produce. Environmentalists claim half the world's population will face water shortage because of climate change by 2080.One in five humans is said to lack access to safe drinking water. The Water Mill is not effective in areas with below about 30 percent relative humidity, but with average relative humidity in England of more than 70 percent that won't be much of an issue here.
Answer: unlimited source
According to the author, the biggest advantage of the machine is its _ .

Article: "A good parent" can be a confusing phrase. It is almost impossible for one person to be "a good parent" at all stages of a child's life. Some parents are at their best before their children begin to speak. Others are most successful before their children enter elementary school. Still others make their finest contribution to older children or teenagers. Every parent can understand one stage of a child's development better than another. It is hard for a person to possess superior capacities throughout the entire period of a child's growth. A mother might be "a good parent" from her baby's birth until it is three; that is the period when it needs her protection and loving care. Then the start of her child's independence might upset and alarm her, and she might then become less helpful for a few years. A father might be awkward and uncomfortable with a younger child, but could turn into an excellent parent when the child is old enough to be taught the skills of cycling, fishing and so on, or to be taken on trips. Some parents feel easier with boys, and others with girls -- and then only at certain ages or stages. It is important for parents to understand and accept their own limitations in these matters, just as they must accept the child's faults of personality and limitations of talent. Otherwise, fathers and mothers will feel guilty and blame themselves for weaknesses that may not be their faults. Much of the guilt experienced by modern parents comes from the mistaken feeling that they ought to be all things at all times to the child, which is clearly mistaken. In past ages, grandparents and uncles and aunts lived with the family, and provided different kinds of support; in our present "nuclear" family, too many roles are demanded of the two parents, which they cannot possibly fulfill.
Answer: parents do not realize they cannot perform equally well through a child's growth
Confusion arises about what it means to be "a good parent" because _ .

Article: A survey suggests that people who have dropped out from high school just earn an average of $9,000 less per year than graduates. Now a new study removes a common belief why they quit. It's much more basic than flunking out . Society tends to think of high school dropouts as kids who just can't cut it. They are lazy, and perhaps not too bright. So researchers were surprised when they asked more than 450 kids who quit school about why they left. "The vast majority actually had passing grades and they were confident that they could have graduated from high school." John Bridgeland, the executive researcher said. About one million teens leave school each year. Only about half of African-American and Hispanic students will receive a diploma , and actually all dropouts come to regret their decision. So, if failing grades don't explain why these kids quit, what does? Again, John Bridgeland: "The most dependable finding was that they were bored." "They found classes uninteresting; they weren't inspired or motivated. They didn't see any direct connection between what they were learning in the classroom to their own lives, or to their career aspirations." The study found that most teens who do drop out wait until they turn sixteen, which happens to be the age at which most states allow students to quit. In the U.S., only one state, New Mexico, has a law requiring teenagers to stay in high school until they graduate. Only four states: California, Tennessee, Texas and Utah, plus the District of Columbia, require school attendance until age 18, no exceptions. Jeffrey Grin, another researcher, says raising the compulsory attendance age may be one way to keep more kids in school. "As these dropouts look back, they realize they've made a mistake. And anything that sort of gives these people an extra push to stick it out and see it through to the end, is probably helpful measure." New Hampshire may be the next state to raise its school attendance age to 18. But critics say that forcing the students unwilling to continue their studies to stay in school misses the point--the need for reform. It's been called for to reinvent high school education to make it more challenging and relevant, and to ensure that kids who do stick it out receive a diploma that actually means something.
Answer: they take no interest in classes
According to researchers' study, most high school students drop out of school because _ .