阅读理解 Learning a second language is tricky at any age (and it only gets tougher the longer you wait to crack open that dusty French book). Now, in a new study, scientists have pinpointed the exact age at which your chances of reaching fluency in a second language seem to plummet: 10.
The study, published in the journal Cognition, found that it's "nearly impossible" for language learners to reach native-level fluency if they start learning a second tongue after age 10. But that's not because language skills start to go downhill. "It turns out you're still learning fast, " says study co-author Joshua Hartshorne, an assistant professor of psychology at Boston College. "It's just that you run out of time, because your ability to learn starts
dropping at around 17 or 18 years old." People who start a few years after age 10 may still become quite good at a language, the authors say, but they are unlikely to become fluent.
Kids may be better than adults at learning new languages for many reasons. Children's brains are more plastic than those of adults, meaning they're better able to adapt and respond to new information. "All learning involves the brain changing, " Hartshorne says, "and children's brains seem to be a lot more adept at changing." Kids may also be more willing to try new things (and to potentially look foolish in the process) than adults are. Their comparatively new grasp on their native tongue may also be advantageous. Unlike adults, who tend to default to the rules and patterns of their first language, kids may be able to approach a new one with a blank slate.
These findings may seem discouraging, but it was heartening for scientists to learn that the critical period for fluent language acquisition might be longer than previously thought. Some scientists believed that the window begins to close shortly after birth, while others stretched it to early adolescence. Compared with those estimates, age 17 or 18 — when language-learning ability starts to drop off— seems relatively old.
For the study, the researchers created an online quiz promising to guess people's native language, dialect and home country based on their responses to English grammar questions. At the end of the quiz, people entered their actual native language, if and when they had learned any others and where they had lived. The quiz went viral: almost 670, 000 people took it, giving the researchers huge amounts of data from English speakers of many ages and backgrounds. Analyzing the responses and grammar mistakes allowed them to draw unusually precise conclusions about language learning.
The findings also offer insights for adults hoping to pick up a new tongue. People fared better when they learned by immersion, rather than simply in a classroom. And moving to a place where your desired language is spoken is the best way to learn as an adult, says Hartshorne.
If that's not an option, you can mimic an immersive environment by finding ways to have conversations with native speakers in their own communities, Hartshorne says. By doing so, it's possible to become conversationally proficient — even without the advantage of a child's brain.

【正确答案】 B

【答案解析】从第5段最后一句话可以得知，研究人员在线测验的目的是通过分析他们的答案和语法错误，精确地得出关于语言学习的结论，因此B项为正确答案；A项为第4段中提到的内容，在线测验并不是为了证明“能使一门语言的习得达到流利程度的关键时期可能要比之前提出的时间长一些”这一论断：C项“分析他们的答案和语法错误”并不是在线测试的目的：D项“得到大量来自不同年龄段和具有不同背景的讲英语的人的研究数据”也是手段，而不是目的。答案为B。