Third, biodiversity is decreasing. Due to urbanization, agricultural development, forest reduction and environmental pollution, the natural area has become smaller and smaller, leading to the extinction of thousands of species. Because the extinction of some species will lead to the disappearance of many molecules that can be used to make new drugs, and also lead to the disappearance of many genes that can help crops overcome bad weather, and even lead to plague. Fourth, the reduction of forest area. In recent decades, the forest area in tropical countries has also been seriously reduced. In 1980- 1990,1500,000 hectares of forest disappeared in the world. At the current rate of forest area reduction, 40 years later, some Southeast Asian countries will never see a tree again. 5. Freshwater resources are threatened. According to experts' estimation, from the beginning of the next century, a quarter of the world will be short of water for a long time. Please remember that we can't make water, we can only try to protect it. Sixth, chemical pollution. Millions of compounds brought by industry exist in air, soil, water, plants, animals and human body. Even the ice sheet, the last large natural ecosystem on earth, has been polluted. Those organic compounds, heavy metals and toxic products are concentrated in the whole food chain, which will eventually threaten the health of animals and plants, lead to cancer and weaken soil fertility. Seven, chaotic urbanization. By the end of this century, there will be 2 1 big cities in the world, and the living conditions of big cities will further deteriorate: congestion, water pollution, poor sanitation and insecurity-the disorderly expansion of these big cities has also destroyed natural areas. Therefore, unrestricted urbanization should be regarded as a new drawback of civilization. Eight, the over-exploitation of the ocean and pollution in coastal areas. Polar ozone hole
Due to overfishing, the fishery resources of the ocean are decreasing at an alarming rate. Therefore, many poor people who live in protein and eat seafood are facing the threat of hunger. The rich heavy metals and organophosphorus compounds in fish may bring serious problems to the health of fish eaters. The coastal areas are under great population pressure. 60% of the world's population is crowded in places less than 100 km from the sea. This crowded population makes these usually fragile places out of balance. Nine, air pollution. The air in most big cities contains many pollutants from heating, transportation and factory production. These pollutants threaten the health of tens of millions of citizens and cause many deaths. Toxic gases are mainly carbon monoxide, sulfur dioxide, nitrogen dioxide and inhalable particles. Ten, the polar ozone hole. Although people have signed the Montreal Protocol, an ozone hole still forms over the earth's poles every spring. The ozone layer in the Arctic is lost by 20% to 30%, and the ozone layer in the Antarctic is lost by more than 5 1%.
Edit the definition of this paragraph.
Environmental protection refers to all human activities that use the theories and methods of environmental science to coordinate the relationship between human beings and the environment, solve various problems and protect and improve the environment. Including administrative, legal, economic, scientific and technical measures, rational utilization of natural resources, prevention of environmental pollution and destruction, in order to maintain and develop ecological balance, expand the reproduction of useful natural resources and ensure the development of human society. Environmental protection involves a wide range and is comprehensive. It involves many fields of natural science and social science, and its unique research object. Environmental protection contains at least three meanings:
Preservation of the natural environment
Prevent the deterioration of the natural environment. Including: protecting green mountains, green waters, blue sky and sea. This involves not privately mining (mining), chopping (trees), dumping (sewage), releasing (polluted gas), overgrazing, overexploiting natural resources, destroying the ecological balance of nature and so on. This level is macroscopic and can only be solved by governments at all levels exercising their functions and carrying out regulation.
Protect human habitation and living environment
Make it more suitable for the needs of human work and labor. This involves all aspects of people's daily necessities, and must meet the requirements of science, hygiene, health and green. This level belongs to the micro level, which can only be solved through the conscious actions of citizens, the protection of government policies and regulations, the guidance of community organizations and education, and the joint efforts of all walks of life.
Protect life on earth
Protection of species, protection of plants and vegetation, return of animals, combination of biodiversity and transgenic protection of endangered organisms.
Reasonable and prudent use, special and special protection for endangered species, restoration of extinct species, expansion of habitat, harmonious coexistence between man and creatures, and no bullying of other species. The relationship between these three levels is: you have me and I have you, each with its own emphasis and unity. The three are not contradictory, let alone antagonistic. As citizens, protecting our living environment means protecting the natural environment indirectly or directly; If we destroy the living environment, we will directly or indirectly destroy the natural environment. As a government, we should not only focus on macro-protection, but also start from micro-level, mobilize and educate the masses, and make environmental protection a conscious action of citizens. 1972 After the United Nations Conference on the Human Environment, the term "environmental protection" was widely used. For example, the former Soviet Union gradually changed the traditional "nature protection" to "environmental protection"; China put forward the policy of "comprehensive utilization" of industrial waste in 1956, and put forward the concept of "three wastes" treatment and recycling in the late 1960s, which changed into the scientific concept of "environmental protection" in the 1970s. According to the Environmental Protection Law of People's Republic of China (PRC), environmental protection includes protecting the natural environment and preventing pollution and other public hazards. In other words, we should use the theories and methods of modern environmental science to better understand and master the causes and harms of pollution and destruction of the environment, protect the environment in a planned way, restore the ecology, prevent the deterioration of environmental quality, control environmental pollution, and promote the coordinated development of human beings and the environment. China attaches importance to environmental protection relatively late, and there is still a gap between governments at all levels, so it is rarely called an environmental protection government. So it's too early to talk about environmental citizens.
Edit this paragraph.
Environmental protection means that human beings consciously protect natural resources, make rational use of natural resources and prevent the natural environment from being polluted and destroyed; It is necessary to comprehensively control the polluted and destroyed environment and create an environment suitable for human life and work. Environmental protection refers to various actions taken by human beings to solve real or potential environmental problems, coordinate the relationship between human beings and the environment, and ensure the sustainable development of economy and society. Its methods and means include engineering technology, administration, law, economy, publicity and education, etc. Its contents mainly include: (1) prevention and control of environmental pollution caused by production and living activities, including prevention and control of "three wastes" (waste water, waste gas and three wastes).
Slag), dust, radioactive substances, noise, vibration, odor and electromagnetic microwave radiation, harmful gases, liquids and noise generated by transportation activities, pollutants discharged by ships at sea, toxic and harmful chemicals used in industrial and agricultural production and people's life, soot, sewage and garbage discharged from urban life; (2) Preventing environmental damage caused by construction and development activities, including preventing environmental pollution and damage caused by large-scale water conservancy projects, railways, highway trunk lines, large-scale ports and docks, airports and large-scale industrial projects, and preventing environmental damage, pollution and impact caused by land reclamation around lakes, development of offshore oil fields, coastal zones and swamps, development of forests and mineral resources, and establishment and construction of new industrial zones and new towns; (3) Protecting the natural environment with special value, including effectively protecting rare species and their living environment, historical sites of special natural development, geological phenomena, landforms and landscapes, etc. In addition, urban and rural planning, controlling soil erosion and desertification, planting trees, controlling population growth and distribution, and rationally allocating productive forces also belong to environmental protection. Environmental protection has become one of the common actions and main tasks of governments and people all over the world. China declared that environmental protection is a basic national policy of China, and formulated and promulgated a series of laws and regulations on environmental protection to ensure the implementation of this basic national policy.
The main responsibilities of editing this paragraph
1) Prevention and control of environmental pollution caused by production and living activities, including prevention and control of "three wastes" (waste water, waste gas and waste residue), dust and radioactive substances discharged from industrial production, noise, vibration, odor and electromagnetic microwave radiation, harmful gases, waste liquid and noise generated from transportation activities, pollutants discharged from ships at sea, toxic and harmful chemicals used in industrial and agricultural production and people's life, and smoke and dust discharged from urban life. (2) Preventing environmental damage caused by construction and development activities, including preventing environmental pollution and damage caused by large-scale water conservancy projects, railways, highway trunk lines, large-scale ports and docks, airports and large-scale industrial projects, and preventing environmental damage, pollution and impact caused by land reclamation around lakes, development of offshore oil fields, coastal zones and marshlands, development of forests and mineral resources, and establishment and construction of new industrial zones and new towns; 3) Protect the natural environment with special value, including providing effective protection for rare species and their living environment, special historical sites of natural development, geological phenomena, landforms and landscapes. In addition, urban and rural planning, controlling soil erosion and desertification, planting trees, controlling population growth and distribution, and rationally allocating productive forces also belong to environmental protection. Environmental protection has become one of the common actions and main tasks of governments and people all over the world. China declared that environmental protection is a basic national policy of China, and formulated and promulgated a series of laws and regulations on environmental protection to ensure the implementation of this basic national policy.
Edit the code of conduct in this paragraph.
1) Saving water is pride-turn off the tap at any time and don't let the water run away in vain. Please?Save?Water
2) Monitor the water source-protecting the water source means protecting your own life; 3) Use more water-don't waste resources, let the water be reused; 4) Stop dripping-check and repair the faucet; 5) Use detergent carefully-use soap as much as possible to reduce water pollution; 6) Care about the air quality-don't forget that you are breathing all the time; 7) Turn off the lights at will-save one degree of electricity. Less pollution 8) Use less electrical appliances-contribute to slowing global warming 9) Use less air conditioners-reduce energy consumption 10) Support green lighting-use energy-saving lamps for everyone 1 1) Use renewable resources-don't wait until the day when energy runs out 12) Do ". Traffic vehicles are proud of 13) being "bike heroes"-protecting the atmosphere from the first step 14) reducing exhaust emissions-drivers' responsibility 15) using unleaded gasoline-drivers' choice 16) using recycled paper-reducing deforestation.
20) Maintain a peaceful environment-let's start from ourselves 2 1) Recognize the "environmental label"-choose green food 22) Use fluorine-free products-protect the ozone layer 23) Choose phosphorus-free washing powder-protect rivers and lakes 24) Buy environmentally-friendly batteries-prevent mercury and cadmium pollution 25) Choose green packaging-reduce garbage disasters 26) Recognize the pollution of green food labels. Use less disposable products-save the earth's resources 29) Bring your own shopping bags-use less plastic bags 30) Use less disposable chopsticks-don't turn the forest into sawdust 32) Use old things skillfully-prolong the life of limited resources 33) Exchange and donation of surplus goods-idle waste, donate glory 34) Recycling waste plastics-developing the "second oil field" 35) Recycling waste batteries
38) Promote garbage sorting and recycling-fight against garbage pollution with little effort 39) Refuse to eat wild animals-change bad eating habits 40) Refuse to use wild animal products-don't let endangered lives die in your hands 4 1) Don't hunt and raise wild animals-protect fragile biological chains 42) Stop poaching and buying and selling wild animals-exercise your sacred rights 43) Be one. Be kind to life and save everything * * * 44) Don't buy rare wooden tools-don't destroy the tropical rain forest 45) Plant trees to protect forests-fight against deserts 46) Adopt trees-be green forest guards 47) Recycle all kinds of wastes-all garbage can be turned into resources.
Edit the range of this paragraph.
Including protecting the earth, protecting the space universe and maintaining the living environment. Land (topography, landforms, etc. ), atmosphere, water, biology (human beings, forests, plants, animals, etc. ), sunlight, nature and artificial external world as a whole. Natural and cultural heritage.
Governance and protection of the earth
The reason why the earth's environmental protection puts governance ahead and protection behind is that the land has been polluted, so it is necessary to emphasize governance and protection at the same time. Strengthen the management of polluted land (land, mountains and continental shelf) and restore its source.
Control and protection of the atmosphere
Limit, reduce emissions, purify the atmosphere, and use natural+artificial methods.
water treatment
Because social production and life are closely related to water, water hunger, water shortage, drought and water pollution are the key points of water, and "water treatment" is the most important and urgent focus of the water family. Therefore, the field of water treatment involves a wide range of applications and constitutes a huge industrial application. There is a tendency to exceed "natural water". The water treatment method includes: (1) sediment filtration, (2) hard water softening, (3) activated carbon adsorption, (4) deionization, (5) reverse osmosis and reverse osmosis; (6) ultrafiltration, (7) distillation, (8) ultraviolet disinfection, (9) biochemical method, etc. And the most novel (10) forward osmosis method, a new natural purification method created by human beings. The natural "forward osmosis" method reduces the secondary and tertiary pollution, consumes energy and warms a bright future. Promote the negative growth of environmental water cost.
Edit the measures in this paragraph.
1. air conditioning is 26 degrees in winter 18 summer, saving hundreds of millions of degrees nationwide. In winter, the air conditioning temperature is adjusted to below 18 degrees. If you feel a little cold, you can put on more clothes. Such a simple measure can save electricity, thus reducing greenhouse gases such as carbon dioxide emitted by coal-fired power generation and slowing down climate warming. In summer, the air conditioning temperature is adjusted to above 26 degrees. The air conditioning load in big cities accounts for about 40%-50% of the maximum power supply load in midsummer. Increasing the air conditioning temperature from 22-24℃ to 26-28℃ can reduce the power load 10%- 15% and reduce the electricity consumption by more than 400-600 million kWh. Sweating in summer is beneficial to people, which can enhance metabolism, regulate endocrine function and promote autoimmunity. 2. Use energy-saving lamps instead of light bulbs, saving electricity by nearly 80%. If you want to buy products that have passed the national energy-saving product certification, you can judge by whether the word "festival" is printed. Under the same luminous flux, energy-saving lamps save 80% electricity compared with incandescent lamps, and the cost of purchasing energy-saving lamps can be recovered from (8 ~ 10) months of energy saving. 3. Garbage classification is not littered for recycling. In garbage, about 50% is biological organic matter, and about 30%-40% is recyclable. In 2000, six kinds of recyclable wastes were produced in China, namely, waste steel 4 1.5-0.43 million tons, waste nonferrous metal 0/0.2 million tons, waste rubber 850,000-920,000 tons, waste plastic 2.3-2.5 million tons and waste glass 0/0.40 million tons. At present, the value of waste that can be used but not used in China reaches 25 billion yuan every year, and about 3 million tons of scrap steel and 6 million tons of waste paper are not recycled. The recovery rate of waste plastics is less than 3%, and the recovery rate of rubber is 3 1%. Only more than 6 billion waste dry batteries contain more than 70,000 tons of zinc and 654.38+10,000 tons of manganese dioxide every year. 4. Turn off the power supply without electrical appliances to save electricity. 10% can see all kinds of electrical appliances at home and office, such as TV and computer. Please turn off the power when not in use. In standby mode, the average power consumption per hour of TV set, air conditioner, monitor, PC host and range hood is 8.07 Joules, 3.47 Joules, 7.69 Joules, 35.07 Joules and 6.06 Joules respectively. Turning off the power can not only save your electricity bill, but also protect the environment. 5. Encourage energy-intensive enterprises to install energy-saving facilities. In recent ten years, due to energy shortage, with the further development of energy saving work. Various new advanced energy-saving kilns are becoming more and more perfect, and the heat loss of kilns is obviously reduced after adopting high-quality insulation materials such as new refractory fibers. Adopt advanced combustion device to strengthen combustion, reduce incomplete combustion and make air-fuel ratio more reasonable. However, the technology of reducing flue gas heat loss and recovering flue gas waste heat is still not progressing fast. In order to further improve the thermal efficiency of the kiln and achieve the purpose of saving energy and reducing consumption, recovering flue gas waste heat is also an important energy-saving way. There are usually two ways to recover flue gas waste heat: one is to preheat the workpiece; The other is to preheat the air for combustion. Flue gas preheating workpiece needs to take up a large volume for heat exchange, which is often limited by the workplace (this method can not be used in batch furnaces). Preheating air is a good way to support combustion. Generally arranged on the heating furnace, it can also strengthen combustion, speed up the heating rate of the furnace and improve the thermal performance of the furnace. This not only meets the process requirements, but also can achieve significant comprehensive energy-saving effect. In addition, since 1950s, preheaters for preheating air have been used in industrial furnaces in China. The main forms are tubular, cylindrical radial and cast iron block heat exchangers, but the heat exchange efficiency is low. In 1980s, domestic heat exchangers, such as jet type, jet radiation type and composite table type, were developed one after another, which mainly solved the problem of medium and low temperature waste heat recovery. The recovery of flue gas waste heat below 100 degrees has achieved remarkable results, and the heat exchange efficiency has been improved. However, at high temperature, it is still limited by the material of heat exchanger, with short service life, heavy maintenance workload or high solid cost, which affects its popularization and use. 265438+At the beginning of the 20th century, gongyi city finally developed Ronghua ceramic heat exchanger. Its production process is basically the same as that of kiln furniture, and thermal conductivity and oxidation resistance are the main application properties of the material. Its principle is to place the ceramic heat exchanger near the outlet of the flue with high temperature, without adding cold air and high temperature protection. When the kiln temperature is 1250- 1450℃, the flue outlet temperature should be 1000- 1300℃, and the waste heat recovered by ceramic heat exchanger can reach 450-750℃. Ceramic heat exchanger has been well developed under the limitation of metal heat exchanger, because it solves the problems of corrosion resistance and high temperature resistance and becomes the best heat exchanger for recovering high temperature waste heat. After years of production practice, it shows that the effect of ceramic heat exchanger is good. Its main advantages are good thermal conductivity, high high temperature strength, good oxidation resistance and thermal shock resistance. Long service life, small maintenance, reliable and stable performance and simple operation. It is the best device to recover the waste heat of high temperature flue gas at present. At present, ceramic heat exchangers can be used in major hot kilns in metallurgy, nonferrous metals, refractories, chemicals, building materials and other industries, and are making great contributions to the cause of energy conservation and emission reduction in the world.
Edit the related concepts in this paragraph.
Environmental cost, also known as environmental degradation cost, refers to the cost of environmental pollution caused by economic activities leading to the decline of the quality of environmental services. The cost of environmental degradation is divided into environmental protection expenditure and environmental degradation cost. Environmental protection expenditure refers to the value actually paid for environmental protection, and environmental degradation cost refers to the value of environmental pollution loss and the value that should be paid for environmental protection. The natural environment mainly provides living space and ecological efficiency, which has the characteristics of long-term repeated use and is similar to the use characteristics of fixed assets. In this way, the cost of environmental degradation caused by economic activity pollution is the cost of environmental degradation, which also has the nature of "depreciation of fixed assets"
Edit the chemical curing agent of sludge in this section.
Especially the solidification of river sludge or urban sewage sludge. With the construction of a large number of urban sewage treatment plants, the sewage treatment capacity and sludge output are increasing. Sludge contains a large number of microorganisms, pathogens, heavy metals and organic pollutants, and its water content is generally above 80%. Improper handling will cause secondary pollution. At present, the main methods of sludge treatment are agriculture, incineration and landfill, and a large amount of sludge is discarded without any treatment. Due to the high water content of sludge, poor soil mechanical properties and high pollutant content, all the current treatment methods have problems such as environmental pollution, high treatment cost and easy to cause landfill engineering geological disasters. Whether sludge can be buried depends on the geotechnical properties of sludge or the mixture of sludge and other additives. When silt is buried, it is required that the shear strength of vane is ≥25kpa and the unconfined compressive strength is ≥50kpa. After conventional dehydration, the water content of sludge is above 80%, and the shear strength of serrated plate is
Edit the relevant laws in this paragraph
1979, China passed the first environmental protection law-People's Republic of China (PRC) Environmental Protection Law (for Trial Implementation). Since the reform and opening up, China has gradually formed a legal system of environmental protection. 1973, the first environmental standard was born in China-the trial standard of industrial "three wastes" discharge. By the end of 1998, China had issued 4 12 national environmental standards over the years, and there are currently 36 1 items, including 80 environmental quality standards, 80 pollutant discharge standards, 230 environmental monitoring method standards, 29 environmental standard sample standards and/kloc-environmental basic standards. At the same time, by 1998, China * * * had promulgated 6 environmental protection laws, 9 environmental resources laws, 34 administrative regulations on environmental protection, more than 90 regulations of environmental protection departments, more than 900 local regulations and local government regulations on environmental protection, and 6 military regulations on environmental protection, and concluded and participated in 37 international environmental conventions, initially forming an environmental protection legal system with China characteristics and becoming a China society. In particular, in order to meet the objective needs of economic development and environmental protection, the NPC Standing Committee adopted the decisions on amending the Law on Prevention and Control of Air Pollution and the Law on Prevention and Control of Water Pollution in 1995 and 1996 respectively. 1In March, 1997, the revised Criminal Law of People's Republic of China (PRC) added the crime of damaging the protection of environmental resources. The basic principles of China's environmental protection law are: coordinated development of economic construction and environmental protection; Prevention first, combining prevention with treatment; Polluter pays; The government is responsible for environmental quality; Rely on the masses to protect the environment. From June 5438 to October 2002, the Law of the People's Republic of China on Environmental Impact Assessment was promulgated, which provided a scientific basis for project decision-making, project site selection, product positioning, construction planning and scale, and environmental monitoring and management after completion.
Edit the relevant institutions in this paragraph.
The United Nations Environment Programme (UNEP- UNEP) was established in 1973, and its headquarters is in Nairobi, Kenya. It is one of only two United Nations agencies in the world with headquarters in developing countries. Membership in UNEP is open to all States Members of the United Nations, members of specialized agencies and members of the International Atomic Energy Agency. By 2009, more than 65,438,000 countries had participated in its activities. In the 2 1 century, when the international community and governments pay more and more attention to the global environmental situation and the prospect of sustainable development in the world, UNEP has received more and more attention and played an irreplaceable key role. China Environmental Protection Federation All-China Environmental Federation (ACEF). ) is a non-profit, national social organization approved by People's Republic of China (PRC) and the State Council, registered in the Ministry of Civil Affairs, headed by the State Environmental Protection Administration, and voluntarily formed by people who are enthusiastic about environmental protection, enterprises and institutions. The purpose of China Environmental Protection Federation is to implement the sustainable development strategy, realize the national environmental and development goals, protect the public and social environmental rights and interests, fully embody the organizational advantages of "Greater China, Greater Environment and Greater Alliance", play the role of a bridge and link between the government and society, and promote the development of environmental undertakings in China and the progress of environmental undertakings for all mankind. China Environmental Protection Industry Association China Environmental Protection Industry Association was established in 1993 (formerly known as 1984). It is a social organization composed of scientific research, design, production, circulation and service units registered in China and industry experts engaged in environmental protection industry in China. It is a cross-regional, cross-departmental and cross-ownership national industry with the qualification of enterprise legal person. China Environmental Protection Industry Association * * has 46 group members (environmental protection industry associations in all provinces, autonomous regions, municipalities directly under the Central Government and sub-provincial cities), with more than 1 100 unit members, and connects with tens of thousands of enterprises through provincial and municipal associations. Environmental Protection China Industry Alliance Environmental Protection China Industry Alliance (EPCIU): abbreviated as Environmental Protection China, is an unincorporated, active and academic non-governmental organization dedicated to "preventing and controlling environmental pollution, improving ecological environment and protecting natural resources". The alliance was jointly initiated by relevant government departments, industry associations, mainstream media and leading enterprises, and received extensive attention and strong support from all walks of life. Alliance purpose: environmental protection makes the world better. Accelerate the development of China's environmental protection industrialization, build a mature environmental protection industrial chain, integrate the resources of government departments, research institutions, environmental protection enterprises, mainstream media and other parties, promote the effective integration of upstream and downstream enterprises in the environmental protection industry, optimize the industrial structure, and promote economic development. China Environmental Culture Promotion Association (CECPA) is affiliated to the Ministry of Environmental Protection of People's Republic of China (PRC). It is a cross-regional, cross-departmental and non-profit national environmental culture organization with legal personality. The association consists of experts and scholars, writers, artists, journalists, publicity and education workers, entrepreneurs and social celebrities. Chinese Society of Environmental Sciences Chinese Society of Environmental Sciences (English name: China Society for Environmental Sciences; English abbreviation: CSES) was approved to be established in May 1978. It is the earliest non-profit national non-governmental science and technology organization in China, specializing in environmental protection. It is a national first-class society under the China Association for Science and Technology, which has the advantages and characteristics of cross-departmental, cross-industry and extensive horizontal contact. The competent business units are China Association for Science and Technology and State Environmental Protection Administration.
Edit the relevant anniversary of this paragraph.
International Wetlands Day February 2nd is the International Wetlands Day. According to the Convention on Wetlands of International Importance Especially as Waterfowl Habitat signed by 197 1 in Ramsar, Iran, wetlands refer to "permanent or temporary swamps, peatlands or static or flowing waters, or fresh water, brackish water or saline water bodies, including water bodies less than 6m at low tide". Wetlands play an important role in protecting biodiversity, especially the survival and migration of birds. World Water Day 1993 65438+ 10/8, the 47th UN General Assembly made a resolution to designate March 22nd as World Water Day every year. The resolution invites governments to carry out some specific activities on this day according to their national conditions to raise public awareness. Starting from 1994, the China Municipal Government changed the time of "China Water Week" to March 22nd-28th every year, which made the publicity activities more prominent on the theme of "World Water Day". World Meteorological Day 1960, the World Meteorological Organization designated March 23rd as "World Meteorological Day" to raise public awareness.
Mathematics teacher's class experience 1
In Yutian No.3 Middle School, I observed two teachers' hi