们知道它的病源，也不了So 解它的治疗方法。of many thousands
terrified people died
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every time there was an
暴乱霍outbreak.每次发时，就有大批惊
恐的John Snow 老百姓死去。the wanted to face challenge and solve this
想诺约problem.翰·斯面对这个挑战，解决这that 个问题。He knew
never be cholera would
its
controlled until
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他知found. was cause道，在找到病源之前，霍乱疫情是无法控制 的。 He became interested inthat theories two how explained
possibly
斯.cholera killed people诺对霍乱致人死地的两种推测都很感兴趣。that first The suggested
---- ---
in cholera multiplied of air. cloud A the floated dangerous
