Today, several of the world's nearly 7,000 languages face a serious risk of extinction. "For example, Ainu, a language in Japan, is now seriously threatened, with only 10 native speakers left," said lead study author Tatsuya Amano at the University of Cambridge in England.
The scientists found that 25 percent of the world's languages are threatened. After identifying where the endangered languages were, they looked for any environmental and social or economic factors those languages might have in common, such as rugged terrain or rapid population growth. "We found that at the global scale, language speaker declines are strongly linked to economic growth-that is, declines are particularly occurring in economically developed regions," Amano said.
One important implication of this new study "is that languages in the tropics and Himalayan region are likely to be increasingly threatened in the near future, because these regions still have many local indigenous languages (土语) with a small number of speakers, and at the same time are experiencing rapid economic growth," Amano said.
Economic growth may endanger languages for a variety of reasons. For instance, speakers of endangered languages may view another more dominant language as offering economic opportunities, and thus forego their own languages. There are other important factors that might endanger languages, the researchers said. For instance, policies regarding how languages are used and taught in schools can be very different among countries and even within each country, and these factors may explain more detailed patterns in language endangerment.
Amano suggested it could be possible to forecast future threats to linguistic diversity. "There exists detailed information on projected future changes in the environment, economies and climates," Amano said. "Using such information, together with the findings of this study and further analysis, we would like to understand what will happen to the world's languages, where it will happen and which languages will be threatened in particular."
The language of Ainu is mentioned in Paragraph l in order to tell us that _______________.

A．Japanese is new seriously threatened

B．few people speak Japanese in the world

C．Japanese is made up of many languages

D．it is most likely to disappear in the future

What may endanger the languages most according to Amano?

A．The diversity of society.

B．The decline of the population.

C．The development of economy

D．The improvement of the environment.

The writer shows us the reasons that languages are endangered by ___________________.

A．offering some examples

B．performing some experiments .

C．telling some interesting stories

D．making a list of important facts .

It can be inferred from the last paragraph that _______________.

A．the study is very important to languages

B．world's languages are developing rapidly

C．it is rather hard for us to protect languages

D．future threats to languages can be predicted