Imagine putting some bacteria in the freezer and taking them out millions of years later to find that they are still alive.

That would be similar to what happened recently, when scientists brought eight-million-year-old bacteria back to life ― simply by thawing them out.

The ancient bacteria were found frozen in the world's oldest known tracts of ice, the glaciers (冰川) of Antarctica.

Professor Bidle and his colleagues found and revived (复活) two samples of bacteria from the glacial ice. The first was a hundred thousand years old, and the second was around eight million years old. The eight-million-year-old bacteria were alive. But their genes were seriously damaged from long exposure to cosmic (宇宙 ) radiation, which is higher at the earth's poles.

Most of the bacteria in the samples probably blew over from African deserts, said Paul Falkowski, a scientist at Rutgers University. Once the bacteria landed on the glacier's snowy surface, they combined with the snow to form ice. "These ices are actually gene banks," he added.

As glaciers and ice caps melt as a result of increasing global warming, large amounts of bacterial genetic material might be washed into the ocean.

These bacteria might get incorporated into today's bacteria in the ocean, or living bacteria from the ice might also grow and have an important effect on the ecosystem.

"How that's going to play out, we don't know," Bidle said. He and Falkowski plan to focus their future work on how current ice melting influences modem bacteria's genetic diversity.

68. Professor Bidle found that the eight-million-year-old bacteria were __.

A. alive with their genes damaged

B. as active as the one-hungred-thousand-year-old ones

C. totally the same as what they used to be

D. harder to revive than the one-hundred-thousand-year-old ones

69. According to Paul Falkowski, the ices in Antarctica are gene banks because ____.

A. there are bacteria from African deserts    B. dead bacteria in them can be easily revived

C. they are fit for people to store bacteria    D. plenty of living bacteria can be found in them

70. Professor Bidle and Paul Falkowski will probably do research into the influences of ____.

A. global warming                         B. bacteria's genetic diversity

C. glacier melting                          D. biological diversity

71. What is the passage mainly about?

A. Ocean exploration.                        B. A scientific plan.

C. A scientific discovery.                   D. An interesting experiment.