1 . Through Snow’s tireless effort, water companies began to sell clean water and the threat of cholera around the world saw a s ______ decrease. (用适当的词填空)

2 . 在自来水公司开始销售干净清洁的水后，世界各地的霍乱威胁大幅减少（see...）。
After the water companies began to sell clean water, the threat of cholera around the world ________.