The publicity theme of this year's World Water Day-water and food security. In response to this theme, students from the environmental protection group of a school tested the water in Youjiang River.

The publicity theme of this year's World Water Day-water and food security. In response to this theme, students from the environmental protection group of a school tested the water in Youjiang River. ( 1 (1) filtration removes solid impurities insoluble in liquid, so the operation of removing insoluble impurities in water samples is filtration; In this process, the function of glass rod is to drain water;

(2)A, it is wrong to ban pesticides and fertilizers, and fertilizers and pesticides should be used reasonably;

B, it is wrong to inhibit the growth of all animals and plants in the water. Some animals and plants in the water can purify water;

C, random discharge of domestic sewage will seriously pollute the water body, so it is wrong;

D, industrial wastewater after purification and then discharge will not pollute the water body, so the practice is correct;

So choose D.

(3) The method to reduce the hardness of water is boiling. Heating and boiling will also make protein lose its physiological activity and play a bactericidal role.

So the answer is: (1) filtering; Drainage;

(2)D。

(3) Boil.