New US research indicates that the absolute humidity, which measures the amount of water present in the air, is the key to reducing the spread of flu.
美国最新研究表明，空气绝对湿度与流感病毒的传播有密切关系。
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They also suggest that, as development has spread, there has been a steady fall in the proportion of the world's population in extreme poverty, although also a rise in the absolute number up to 1980.