reduce a fraction to its lowest terms

例句：

1. 1.The amount of water we use is reducing every year.
   我们使用的水量每年在减少。
2. 2.The cost of living has reduced significantly since the economy improved.
   自从经济好转，生活成本已经显著降低。
3. 3. The population of the city is reducing due to a decrease in birth rates.
   由于出生率下降，该城市的人口正在减少。