Climate change connected with the reduction of wetlands at the source of the country's two longest rivers， the Yangtze and the Yellow， has reduced the volume of water flowing into them， scientists said. Scientists studied changes over past 40 years to the wetlands on the cold Qinghai­Tibet Plateau in west China where the two rivers have their sources. They found the wetlands on the plateau have shrunk (减少) more than 10 percent over the past four years. The wetlands at the source of the Yangtze have suffered the most， decreasing by 29 percent. About 17.5 percent of the small lakes at the source of the Yangtze have dried up， the scientists said. “The wetland plays a key role in holding water and changing the water volume of the rivers，” Wang Xugen， a researcher， said. “The reduction of the wetland on the plateau is closely connected with global warming，” Wang said， adding that even though rainfall has increased in the area， the reduction of the wetland has reduced the flow of the Yangtze and the Yellow. Records by the weather station at the head of the Yangtze showed yearly rainfall at its source increased from 260 mm during 1991—2000 to 323 mm in the period 2001—2006. “But the increased rainfall didn't lead to more water's flowing into the rivers because the evaporation (蒸发) was so fast as a result of global warming，” Li Shijie， a researcher， said. Another study showed global warming had caused glaciers to get smaller， frozen earth to melt， grasslands to turn yellow and rivers to dry up. The Qinghai­Tibet Plateau used to have 36 000 glaciers covering an area of 50 000 sq km. In the past 100 years， their area has been reduced by 30 percent. 60.According to the passage， the true statement of the following is that　　　　. A.the wetlands at the source of the Yellow have decreased by 29 percent B.there's no more water in about 17.5 percent of the small lakes at the source of the Yangtze C.the reduction of the wetland on the plateau has nothing to do with global warming D.yearly rainfall has increased from 260 mm to 323 mm in the past 15 years 61.Which of the following is NOT the result of global warming？ A.Frozen earth melts.  B.Evaporation becomes faster. C.Sea level rises.      D.Plants grow better in greenhouses. 62.The area that the glaciers of the Qinghai­Tibet Plateau cover is now about　　　　sq km. A.35 000  B.12 000  C.15 000  D.17 000 63.In the passage，　　　　plays a most important part in holding water and changing the volume of the rivers. A.yearly rainfall  B.the evaporation  C.the wetland  D.climate change