Speaking two languages rather than just one has obvious practical benefits in an increasingly globalized world．But in recent years, scientists have begun to show that the advantages of bilingualism （双语能力） are even more important than being able to converse with a wider range of people．Being bilingual, it turns out, makes you smarter．It can have a deep effect on your brain, improving skills not related to language and even protecting against a serious mental disorder in old age．

This view of bilingualism is different from the understanding of bilingualism through much of the 20th century．Researchers, educators and policy makers long considered a second language to be an interruption that prevented a child's school work and ability to think and understand things．They were not wrong about the interruption: there is ample evidence that in a bilingual \s brain both language systems are active even when he is using only one language, thus creating situations in which one system disturbs the other．But this interruption, researchers are finding out, isn't so much a disturbance．It forces the brain to solve inside conflict, giving the mind a workout that strengthens its thinking muscles．

The key difference between bilinguals and monolinguals may be more basic: a heightened ability to monitor the environment．"Bilinguals have to switch languages quite often—you may talk to your father in one language and to your mother in another language," says Albert Costa, a researcher at the University of Pompea Fabra in Spain．

"It requires keeping track of changes around you in the same way that we monitor our surroundings when driving．" In a study comparing German-Italian bilinguals with Italian monolinguals on monitoring tasks, Mr．Costa and his colleagues found that the bilingual subjects not only performed better, but they also did so with less activity in parts of the brain involved in monitoring, showing that they did better in it．

1.From the passage we can learn that experts used to believe that ______．

A．interruption forced a bilingual's brain to strengthen its thinking ability

B．a second language stopped children's studying as well as mental development

C．using two languages annoyed the children who have trouble in learning skills

D．language systems were busy in a bilingual's brain when he was using languages

2.The underlined word "switch" in Paragraph 3 probably means "______"．

A．change      B．use         C．speak     D．study

3.What is the author's attitude towards bilingualism?

A．Cautious．  B．Doubtful．   C．Concerned．  D．Favourable．

4.Which of the following would be the best title for the passage?

A．How Bilinguals Use Languages    

B．What Bilingualism Is Really about

C．Why Bilinguals Are More Intelligent   

D．When People Learn a Second Language