No one understood cholera and every time it came, thousands died. Neither its cause 61.______ its cure was understood. Queen Victoria's doctor, John Snow, wanted to find 62.______ how it was caused. When the disease came to London again in 1854, Snow noticed that most of the 500 people 63.______ died had drunk water from a water pump in Broad Street.
Two other deaths were linked to the Broad Street outbreak. A woman and her daughter used the water from Broad Street pump and died. With the 64.________(support) evidence, he was able to announce 65._______ certainty that the water carried the virus.
He concluded that the water was 66.___________(blame) and found that the pump's water came from a river 67.__________(pollute) by the dirty water from London dirty. After he told the 68.____________ (astonish) people to remove the handle from the pump and stopped people from using the pump, people 69.___________ (gradual) stopped dying.
Snow suggested all source of water should be checked and water companies take care not to supply people with dirty water. In this way, cholera ___________(defeat).