根据以下材料,回答48-51题 In 1542, Francisco de Orellana led the first European voyage down the Amazon River.During thisvoyage the explorers met a lot of resistance (抵抗) from the local Indians.In one particular tribe thewomen fighters were so fierce that they drove their male fighters in front of them with spears.Thus theriver was named after the famous women fighters of the ancient Greek stories, the Amazons. This voyage also started our wonder of the greatest river and the largest area of rainforest in theworld.About 20% of all fresh water carried to the oceans is from the Amazon River.The Amazon basinis the world' s largest, about the size of Europe.The river is a product of the rainy season, which bringshuge rains every summer.This also produces a large area of rainforest, which supports the largestnumber of diverse plants and animals of any area in the world. The Amazon rainforest is also important when it comes to the future of global warming, as it is ahuge natural store of carbon.Up until recently it was thought that the Amazon had fully grown and thuscould not take up any more CO2.Experiments have shown this could be wrong and that the Amazonrainforest might be sucking up an additional five tons of CO2 from the atmosphere per hectare (公顷)per year.This is because plants react favorably to increased CO2; because it is the raw material forphotosynthesis (光合作用), the more of it the better.So having more CO2 in the atmosphere acts like afertilizer, stimulating plant growth.Because of the size of the Amazon rainforest, it seems that presentlyit is taking up a large percentage of our CO2 pollution in the atmosphere, about 75% of the world's carpollution.