Left alone, it was assumed, the world's rain forests would not only flourish but might even rescue us from disaster by absorbing the excess carbon dioxide and other planet-warming greenhouse gases.
出自-2013年6月阅读原文
For a start, all animals, such as cows, pigs and sheep, always gas limed methane, which is the second most common green house gas after carbon dioxide.
出自-2013年6月听力原文
Many environmental experts now believe that methane is more responsible for global warming than carbon dioxide
出自-2013年6月听力原文