A、Radio waves. B、Sound waves. C、Robots. D、Satellites. A细节辨认题。短文开头部分提到，在20世纪70年代，科学家们通过可以穿透冰层的无线电波首次发现了沃斯托克湖。

While some scientists explore the surface of Antarctica, others are learning more about a giant body of water four kilometers beneath the ice pack. Scientists first discovered Lake Vostok in the 1970s by using radio waves that penetrate the ice. Since then they have used sound waves and even satellites to map this massive body of water.
   How does the water in Lake Vostok remain liquid beneath an ice sheet? The thick glacier above acts like an insulating blanket and keeps the water from freezing, says Martin Siegert, a glaciologist from the University of Wales. In addition, geothermal heat from deep within the Earth may warm the hidden lake. The scientists suspect that micro-organisms may be living in Lake Vostok, closed off from the outside world for more than two million years. Anything found there will be totally alien to what’s on the surface of the Earth, says Siegert. Scientists are trying to find a way to drill into the ice and draw water samples without causing contamination. Again, robots might be the solution. If all goes as planned, a drill-shaped robot will melt through the surface ice. When it reaches the lake, it will release another robot that can swim in the lake, take pictures and look for signs of life. The scientists hope their discoveries will shed light on life in outer space which might exist in similar dark and airless conditions. Recently, close-up pictures of Jupiter’s moon Europa showed signs of water beneath its icy surface. Once tested in Antarctica, robots could be sent to Europa to search for life there, too.
   Questions 9 to 11 are based on the passage you have just heard.
   9. What did scientists first use to discover Lake Vostok in the 1970s?
   10. What do scientists think about Lake Vostok?
   11. What do the scientists hope their discoveries will do?