previous studies, she finds the speed of breaking down in this one exciting. The next step, DeBruyn says, will be to identify the cause of the breakdown. Is it an enzyme produced by the worm itself or by its gut microbes(肠道微生物)?

　　Bertocchini agrees and hopes her team's findings might one day help employ the enzyme to break down plastics in landfills. But she expects using the chemical in some kind of industrial process - not simply ＂millions of worms thrown on top of the plastic.＂

28. What can we learn about the worms in the study?

　　A. They take plastics as their everyday food. B. They are newly evolved creatures.

　　C. They can consume plastics. D. They wind up in landfills.

29. According to Jennifer DeBruyn, the next step of the study is to .

　　A. identify other means of the breakdown B. find out the source of the enzyme

　　C. confirm the research findings D. increase the breakdown speed

30. It can be inferred from the last paragraph that the chemical might .

　　A. help to raise worms B. help make plastic bags

　　C. be used to clean the oceans D. be produced in factories in future

31. What is the main purpose of the passage?

　　A. To explain a study method on worms.

　　B. To introduce the diet of a special worm.

　　C. To present a way to break down plastics.

　　D. To propose new means to keep eco-balance.

　Taktak tabulaba?

You probably don't know how to answer that question---unless you happen to be one of the about 430 people in the world who speak a language called Matukar Panau. Then you would know it means "What are we doing?" Matukar Panau is one of the world's rarest languages. It is spoken in just two small coastal villages in Papua New Guinea.

Several years ago, David Harrison, a language expert didn't know much about Matukar Panau either. No one had ever recorded or even studied its words and rules. With so few speakers, the language risked disappearing soon. It was endangered.

Harrison didn't want that to happen to Matukar Panau. So in 2009, he set out for Papua New Guinea. His goal: use modern technology to help the remaining speakers preserve their native tongue.

But Matukar Panau is far from the only language facing loss. Studies suggest that by the end of this century, nearly half of the 7,000 languages now spoken worldwide could disappear. They're in danger partly because the only people left speaking them are elderly adults, Harrison says. When those individuals die, their language will die with them. In addition, children may discard a native language and instead use more common global languages, such as Chinese, English or Spanish.

In the United States alone, 134 native American languages are endangered. Harrison says, "language hotspots" exist all over the world. These are places with endangered languages that