人口地理研究对国家和地区的社会经济决策和发展具有重要意义。水资源和耕地资源是制约一个

Dr.Jack Todd is very interested in clean water .__小题1:_,so it's natural that he is to developer of a small and affordable system(系统）to clean waste water, His “Living  Machine" can clean wastewater in your home or in your business.
__小题2:_ The wastewater goes into a big plastic tank where bacteria(细菌）start to break down the waste.A few days later after it is dealt with, the water is brought into a greenhouse filled with plants and fish.With the help of sunlight, the plants and animals remove more chemicals from the water,making it cleaner,Then the water can be reused for washing or bathing _小题3:__ but the water is clean enough for watering the flowing, washing the dog, or even for bathing or swimming.
The advantage of this technology is that it is affordable and good for the environment. __小题4:__. It can help to use less fresh water, and it can help keep the water supply unpolluted.

A.    If enough homes and businesses use “Living Machines” B.     People like to plant trees around their houses C.     He is also interested in saving money D.    It cannot be used for drinking or cooking E.     The “Living Machine” is a system for cleaning wastewater