loadingbegin his enquiry.因此，
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暴1854年伦敦再次在斯·发霍乱的时候，约翰诺着手准备对此进行disease the 调研。As through quickly spread
neighbourhoods, poor
gather began to he 在霍乱当
information.贫民区迅速蔓延的时斯诺就开始收·候，约翰资料。集In two
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the particular
streets,
cholera outbreak was so
than that more severe
ten died people 500 in
他发现特别在两days.条街道上霍乱流行的天之内就10在很严重，He 了
500多。人去死find determined to was 他决心要查明why.out 其原因。
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a he on marked First places map exact the dead all where the 首先，people had