The     1     (true) was that the water from the Broad Street pump     2     (infect) by waste. Moreover, Snow was later able to show     3     link between other cases of cholera and the different water companies in London. Some companies sold water from the River Thames     4     was polluted by raw waste. The people who drank this water were much more likely to get cholera than those who drank pure or     5     (boil) water.

Through Snow’s     6     (tire) efforts, water companies began to sell clean water, and the threat of cholera around the world saw a     7     (substance) decrease.     8    , cholera is still a problem. Each year, millions of people around the world get cholera and many die     9     it. Fortunately, we now know how     10     (prevent) cholera, thanks to the work of John Snow. Moreover, in his use of maps and statistics, Snow transformed the way scientists study diseases. For this reason, Snow is considered the father of modern epidemiology.

    1     is known to all, China is a large country     2     agriculture. Science of farming was first     3     (study) here.

Jia Si-xie, living     4     the 6th century AD, was one of the farming pioneers（先驱者）. After he finished his work for the government, he spent his time     5     his research into agriculture. He studied     6     to keep seeds, how to improve soil conditions and so on.

During the years 533~544, he wrote a book     7     (call) Qi Min Yao Shu ,    8     is about both farming and gardening,     9     (include) advice on how to grow green vegetables, how to keep fish in lakes, and so on. It was considered to be     10     important summary of farming knowledge.