Mr.Obama is said to have declared that the United States and Cuba are "on a path of change", while reminding his fellow heads of state that the democratic process that brought them into office does not exist in Cuba.

VOA: standard.2009.04.18

It's nR log of p2 over p1 for the process where there's a pressure change.

结果是dS等于nR乘以p2除以p1的对数,这是对压强变化的结果。

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