12, with the development of township enterprises, wastewater is discharged randomly; With the development of agriculture, the pollution of pesticides and fertilizers is disorderly discharged; With the sharp increase of water consumption in the Yellow River basin, all localities are "chasing and intercepting" the rainwater that once flowed into the Yellow River.

Greatly reduced the inflow of the Yellow River; The so-called "dry farming" has been widely popularized in Gansu and Ningxia, turning the arid soil into pieces of "sponge"; Groundwater exploitation, soil and water conservation, greening and other ecological water directly affect the water quantity of the Yellow River.

13, using examples, serial numbers, classification and comparison methods; Have the function of emphasis;

Pollution in the Pearl River waters caused a large number of continuous deaths of 9 kinds of economic fish and 25 kinds of economic shrimps, such as Sparidae, Lithocarpus, Squid, Penaeus China, etc., resulting in a sharp decline in migration and spawning of lionfish and mackerel. The famous "Wanshan fishing season" here is no longer the flood season. Analysis: It shows that the Pearl River water pollution is extremely serious, and a large number of fish die. The species of fish and shrimp are listed, and it is emphasized that with the rapid development of industry and weak awareness of environmental protection, water resources are seriously polluted.

14, no, because it is reserved in the article that the phenomenon of dry season often occurs, not every year, sometimes for several years.

15, chemical pool should be built to prevent sewage from being discharged into rivers. The government should strictly plan whether the industry meets the requirements of protecting the environment and ecology, such as the emission of waste gas and heavy metals. The government should popularize environmental protection knowledge. The government should plan for farmers how to prevent chemical fertilizers from flowing into rivers and oceans.