Just a year ago，the colors were bright under the waves.Now it's gray - the Maldivian reef is dead.The coral is killed by the pressure of rising temperatures.
   Coral reefs are areas underwater where small creatures live.The coral is hard material formed on the bottom of the sea by the skeletons of those creatures.But the world has lost about half its coral reefs in the last 30 years.Scientists are working to prevent their destruction.Due to global warming，over 90 percent of corals are expected to die by 2050. "To lose coral reefs is to fundamentally undermine the health of a very large proportion of the human race，" said Ruth Gates，director of the Hawaii Institute of Marine Biology.
   Why are coral reefs important？Coral reefs support a fourth of all marine species，as well as half a billion people worldwide.They serve as barriers to protect coastlines from the storms.They provide billions of dollars from tourism，fishing and other trade.They are also used in medical research for cures for diseases. "Everyone should be concerned，" said biologist Ove Guldberg at Australia's University of Queensland. "This is not just some distant dive destination.This is the basic structure of the ecosystem we depend on."
   The ocean is getting warmer.A rising temperature of just one to two degree Celsius can force coral to expel the algae（驅(qū)逐海藻）that live there.This leaves their white skeletons uncovered.It is a process called "bleaching".Sixteen percent of the world's corals died of bleaching in 1998.The problem has become much worse in recent years.
   "We've lost 50 percent of the reefs，but that means we still have 50 percent left，" said Ruth Gates，who is working in Hawaii to breed corals that can better withstand increasing temperatures.She is also trying to "train" corals to survive rising temperatures.Gates says it is time to start "thinking outside the box"- find creative ways to help them.

（1）The underlined word "undermine" in paragraph 2 means .
A．weaken
B．regain
C．promote
D．overlook
（2）What's the major concern of the scientists like Ove Guldberg？
A．People won't find a dive destination in the future.
B．The effort to save corals will turn out to be fruitless.
C．The destruction of coral reefs will affect the earth ecosystem.
D．The bright sea has lost its charm because of those dead corals.
（3）The fourth paragraph is mainly about .
A．the harm of algae
B．the process of "bleaching"
C．the importance of coral reefs
D．the change of ocean temperature
（4）Ruth Gates' attitude towards the protection of corals is .
A．proud
B．cautious
C．optimistic
D．casual

【考點(diǎn)】說明文．

【答案】A；C；B；C