A、The willingness to learn. B、The brain structure. C、The time they spend. D、The effort they spare. B

Neuroscientists have long observed that learning a language presents a different set of opportunities and challenges for adults and children.(19)Adults easily grasp the vocabulary needed to find a grocery store or order food in a restaurant, but children have a born ability to pick up on subtle differences of language that often confuse adults. For example, within months of living in a foreign country, a young child may speak a second language like a native speaker.(20)Experts believe that brain structure plays an important role in this " sensitive period" for learning languages, which is believed to end around 18 years old. The young brain is equipped with neural circuits that can analyze sounds and build a coherent set of rules for constructing words and sentences out of those sounds. Once these language structures are established, it’s difficult to build another one for a new language. In a new study, a team of neuroscientists and psychologists from Massachusetts Institute of Technology(MIT)discovered another factor that contributes to adults’ language difficulties:(21)When learning certain elements of language, adults’ more highly developed mental skills actually get in the way. The researchers discovered that the harder adults tried to learn an artificial language, the worse they were at understanding the language’s structures.(22)In 1990, linguist Elissa Newport pointed out that adults have trouble learning the subtle points in a new language because they try to analyze too much information at once. They tend to throw all of that brain power at learning a second language. This high-powered processing may actually interfere with certain elements of learning a language.
19. In which aspect of learning can adults do really well?
20. What is mentioned as the major cause for people to perform differently in learning languages?
21. What new findings did the researchers from MIT find?
22. What is linguist Elissa Newport’s theory?