目前我国已有200多个城市供水不足,其中40个城市严重缺水,如北京、天津、上海等大城市已面临用水危机,预计全国每天缺水1000多万吨,因此,节约用水是当务之急。然而有许多大型精密仪器是靠大量自来水冷却 At present, there are more than 200 cities in China lack of water supply, 40 of which are seriously deprived of water. Large cities such as Beijing, Tianjin, and Shanghai have already faced a water crisis. The country is expected to have more than 10 million tons of water a day. Therefore, water conservation is a top priority. However, there are many large precision instruments that are cooled by a large amount of tap water.