2013
高考英语二轮阅读理解精选（34）及答案 a in south america, the rich soil of the amazon river basin （流域） in brazil is known as ''black gold"．scientists found that the secret of this rich soil was charcoal．local people made it from animal bones and tree branches．they mixed the charcoal with the soil about 1,500 years ago． now．scientists in the united states have done a modern demonstration．they say charcoal
