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Do you think John Snow would have solved this problem without map? give a reason.

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Cholera was a 19th century disease. what disease do you think is similar to cholera today? why?

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三．句式点击

1. With this extra evidence John Snow was able to announce with certainty that polluted water carried the virus.

with this extra evidence 有了这个额外的证据；with certainty 肯定地，有把握地

在句中作状语，相当于副词.

that 引导宾语从句

polluted 过去分词作定语

2. So many thousands of terrified people died every time there was an outbreak.

terrified 过去分词作定语

every time 短语充当连词作用，还有 the moment/ minute /second;