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名词解释题
土壤有机质半减期 half-life of soil organic matter
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自由基具有下列哪种特性( )A、奇数电子，高化学活性，半减期极短，无顺磁性B、奇数电子，低化学活性，半减期极短，有顺磁性C、奇数电子，高化学活性，半减期极短，有顺磁性D、奇数电子，低化学活性，半减期极长，有顺磁性E、奇数电子，高化学活性，半减期极长，有顺磁性
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根据文章，回答 67～70 问题DHave you ever noticed the colour of the water in a river or stream after a heavy rainfall? What do you think caused this change in colour? It is soil that has been washed into the river from the riverbank or from t}le nearby fields．Components of SoftSoil is made up of a number of layers(层)，each having its own distinctive colour and texture．The upper layer is known as the litter．It acts like a blanket．limiting temperature changes and reducing water loss．The topsoil layer is made up of small particles of rock mixed with rotten plant and animal matter called humus(腐殖质)，which is black and gives the topsoil its dark colour．This layer is usually rich in nutrients，oxygen，and water．Below the topsoil is the subsoil，a layer that contains more stones mixed with only small amounts of organic matter．This layer is lighter in colour because of the lack of humus．Beneath the soil lies a layer of bedrock．Soil forms from the bottom up．Over time bedrock is attacked by rain, wind，frost, and snow．It is gradually broken down into smaller particles in a process called weathering．Plants begin to grow，and rotten materials enrich the topsoil．Most of the soil in Eastern Canada．for example．Was formed from weathered rock that was exposed when the ice disappeared l2．000 years ag0．Water Beneath the SoilSurface water collects and flows above the ground in lakes．ponds．and rivers．Once in the soil or rock，it is called groundwater．Gravity pulls groundwater through the soil in a process called percolation(渗透)．Eventually the water reaches a layer called the water table．Under this is bedrock through which water cannot percolate．As water percolates downward，it dissolves organic matter and minerals from the soil and carries them to deeper layers．This causes a serious problem because plants require these nutrients for growth.Soil pHSoil can be acidic．neutral．or basic．The pH of the soil is determined by the nature of the rock．from which it was formed．and by the nature of t}le plants that grow and rot in it．The acidity of rain and snow can lower the pH of the groundwater that enters the soil．By burning fossil fuels such as coal，oil and gasoline，humans have been contributing to higher levels of acidity in many soils．When fossil fuels are burned．gases are released into the air and then fall back to earth as acid rain．Acid soil increases出e problem of carrying nutrients to lower soil levels．As nutrients are removed，soil is less fertile．Plants grow more slowly in acidic soil，and also become easily attacked by diseases．第12题：The layer of soil that provides necessary nutrients for plant growth is called．A．1itterB．topsoilC．humusD．subsoil
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The underlined word “dissolve” is used to express the idea that organic matter and minerals from soil are .A. rushed away into the riverB. cleaned and purified by waterC. destroyed and carried away by waterD. mixed with water and become part of it
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Organic Food:Why?1 Europe is now the biggest market for organic food in the world,expanding by 25 percent a year over the past 10 years.So what is the attraction of organic food for some people?The really important thing is that organic sounds more"natural".Eating organic is a way of defining oneself as natural,good,caring, different from the junk-food-eating masses.2 Unlike conventional farming,the organic approach means farming with natural,rather than man- made , fertilisers and pesticides. Techniques such as crop rotation（轮种）improve soil quality and helporganic farmers compensate for the absence of man-made chemicals.As a method of food production,organic is,however,inefficient in its use of labour and land;there are severe limits to how much food can be pro- duced.Also,the environmental benefits of not using artificial fertilisers are tiny compared with the amount of carbon dioxide emitted（排放）by transporting food.3 Organic farming is often claimed to be safer than conventional farming. Yet studies into organic farming worldwide continue to reject this claim.An extensive review by the UK Food Standards Agency foundthat there was no statistically significant difference between organic and conventional crops.Even where re-sults indicated there was evidence of a difference,the reviewers found no sign that these differences would have any noticeable effect on health.4 The simplistic claim that organic food is more nutritious than conventional food was always likely to be misleading. Food is a natural product,and the health value of different foods will vary for a number of rea-sons,including freshness,the way the food is cooked,the type of soil it is grown in,the amount of sunlight and rain crops have received,and so on.Likewise,the flavour of a carrot has less to do with whether it was fertilised with manure（粪便）or something out of a plastic sack than with the variety of carrot and how long ago it was dug up.5 The notion that organic food is safer than"normal"food is also contradicted by the fact that many of our most common foods are full of natural toxins（毒素）.As one research expert says : " People think that the more natural something is,the better it is for them.That is simply not the case.In fact,it is the opposite that is true:the closer a plant is to its natural state,the more likely it is that it will poison you.Naturally, many plants do not want to be eaten,so we have spent 10,000 years developing agriculture and breeding out harmful traits from crops."Paragraph 4________A:Factors That Affect Food Health ValueB:Main Reason for the Popularity of Organic FoodC:Testing the Taste of Organic FoodD:Research Into Whether Organic Food Is Better E:Necessity to Remove Hidden Dangers From FoodF:Description of Organic Farming
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Organic Food:Why?1 Europe is now the biggest market for organic food in the world,expanding by 25 percent a year over the past 10 years.So what is the attraction of organic food for some people?The really important thing is that organic sounds more"natural".Eating organic is a way of defining oneself as natural,good,caring, different from the junk-food-eating masses.2 Unlike conventional farming,the organic approach means farming with natural,rather than man- made , fertilisers and pesticides. Techniques such as crop rotation（轮种）improve soil quality and helporganic farmers compensate for the absence of man-made chemicals.As a method of food production,organic is,however,inefficient in its use of labour and land;there are severe limits to how much food can be pro- duced.Also,the environmental benefits of not using artificial fertilisers are tiny compared with the amount of carbon dioxide emitted（排放）by transporting food.3 Organic farming is often claimed to be safer than conventional farming. Yet studies into organic farming worldwide continue to reject this claim.An extensive review by the UK Food Standards Agency foundthat there was no statistically significant difference between organic and conventional crops.Even where re-sults indicated there was evidence of a difference,the reviewers found no sign that these differences would have any noticeable effect on health.4 The simplistic claim that organic food is more nutritious than conventional food was always likely to be misleading. Food is a natural product,and the health value of different foods will vary for a number of rea-sons,including freshness,the way the food is cooked,the type of soil it is grown in,the amount of sunlight and rain crops have received,and so on.Likewise,the flavour of a carrot has less to do with whether it was fertilised with manure（粪便）or something out of a plastic sack than with the variety of carrot and how long ago it was dug up.5 The notion that organic food is safer than"normal"food is also contradicted by the fact that many of our most common foods are full of natural toxins（毒素）.As one research expert says : " People think that the more natural something is,the better it is for them.That is simply not the case.In fact,it is the opposite that is true:the closer a plant is to its natural state,the more likely it is that it will poison you.Naturally, many plants do not want to be eaten,so we have spent 10,000 years developing agriculture and breeding out harmful traits from crops."Techniques of organic farming help________.A:affect their nutritional contentB:poison youC:improve soil qualityD:be eatenE:show that organic crops are safer than conventional ones F: be specially trained
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Organic Food:Why?1 Europe is now the biggest market for organic food in the world,expanding by 25 percent a year over the past 10 years.So what is the attraction of organic food for some people?The really important thing is that organic sounds more"natural".Eating organic is a way of defining oneself as natural,good,caring, different from the junk-food-eating masses.2 Unlike conventional farming,the organic approach means farming with natural,rather than man- made , fertilisers and pesticides. Techniques such as crop rotation（轮种）improve soil quality and helporganic farmers compensate for the absence of man-made chemicals.As a method of food production,organic is,however,inefficient in its use of labour and land;there are severe limits to how much food can be pro- duced.Also,the environmental benefits of not using artificial fertilisers are tiny compared with the amount of carbon dioxide emitted（排放）by transporting food.3 Organic farming is often claimed to be safer than conventional farming. Yet studies into organic farming worldwide continue to reject this claim.An extensive review by the UK Food Standards Agency foundthat there was no statistically significant difference between organic and conventional crops.Even where re-sults indicated there was evidence of a difference,the reviewers found no sign that these differences would have any noticeable effect on health.4 The simplistic claim that organic food is more nutritious than conventional food was always likely to be misleading. Food is a natural product,and the health value of different foods will vary for a number of rea-sons,including freshness,the way the food is cooked,the type of soil it is grown in,the amount of sunlight and rain crops have received,and so on.Likewise,the flavour of a carrot has less to do with whether it was fertilised with manure（粪便）or something out of a plastic sack than with the variety of carrot and how long ago it was dug up.5 The notion that organic food is safer than"normal"food is also contradicted by the fact that many of our most common foods are full of natural toxins（毒素）.As one research expert says : " People think that the more natural something is,the better it is for them.That is simply not the case.In fact,it is the opposite that is true:the closer a plant is to its natural state,the more likely it is that it will poison you.Naturally, many plants do not want to be eaten,so we have spent 10,000 years developing agriculture and breeding out harmful traits from crops."The weather conditions during the growth of crops________.A:affect their nutritional contentB:poison youC:improve soil qualityD:be eatenE:show that organic crops are safer than conventional ones F: be specially trained
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共用题干
Organic Food:Why?1 Europe is now the biggest market for organic food in the world,expanding by 25 percent a year over the past 10 years.So what is the attraction of organic food for some people?The really important thing is that organic sounds more"natural".Eating organic is a way of defining oneself as natural,good,caring, different from the junk-food-eating masses.2 Unlike conventional farming,the organic approach means farming with natural,rather than man- made , fertilisers and pesticides. Techniques such as crop rotation（轮种）improve soil quality and help organic farmers compensate for the absence of man-made chemicals.As a method of food production,organic is,however,inefficient in its use of labour and land;there are severe limits to how much food can be pro- duced.Also,the environmental benefits of not using artificial fertilisers are tiny compared with the amount of carbon dioxide emitted（排放）by transporting food.3 Organic farming is often claimed to be safer than conventional farming. Yet studies into organic farming worldwide continue to reject this claim.An extensive review by the UK Food Standards Agency found that there was no statistically significant difference between organic and conventional crops.Even where re- sults indicated there was evidence of a difference,the reviewers found no sign that these differences wouldhave any noticeable effect on health.4 The simplistic claim that organic food is more nutritious than conventional food was always likely to be misleading. Food is a natural product,and the health value of different foods will vary for a number of rea- sons,including freshness,the way the food is cooked,the type of soil it is grown in,the amount of sunlight and rain crops have received,and so'on.Likewise,the flavour of a carrot has less to do with whether it was fertilised with manure（粪便）or something out of a plastic sack than with the variety of carrot and how long ago it was dug up.5 The notion that organic food is safer than"normal"food is also contradicted by the fact that many of our most common foods are full of natural toxins（毒素）.As one research expert says: "People think that the more natural something is,the better it is for them.That is simply not the case.In fact,it is the opposite that is true:the closer a plant is to its natural state,the more likely it is that it will poison you.Naturally, many plants do not want to be eaten,so we have spent 10,000 years developing agriculture and breeding out harmful traits from crops."Paragraph 1_______A:Factors That Affect Food Health ValueB:Main Reason for the Popularity of Organic FoodC:Testing the Taste of Organic FoodD:Research Into Whether Organic Food is BetterE:Necessity to Remove Hidden Dangers From FoodF:Description of Organic Farming
考题
共用题干
Organic Food:Why?1 Europe is now the biggest market for organic food in the world,expanding by 25 percent a year over the past 10 years.So what is the attraction of organic food for some people?The really important thing is that organic sounds more"natural".Eating organic is a way of defining oneself as natural,good,caring, different from the junk-food-eating masses.2 Unlike conventional farming,the organic approach means farming with natural,rather than man- made , fertilisers and pesticides. Techniques such as crop rotation（轮种）improve soil quality and help organic farmers compensate for the absence of man-made chemicals.As a method of food production,organic is,however,inefficient in its use of labour and land;there are severe limits to how much food can be pro- duced.Also,the environmental benefits of not using artificial fertilisers are tiny compared with the amount of carbon dioxide emitted（排放）by transporting food.3 Organic farming is often claimed to be safer than conventional farming. Yet studies into organic farming worldwide continue to reject this claim.An extensive review by the UK Food Standards Agency found that there was no statistically significant difference between organic and conventional crops.Even where re- sults indicated there was evidence of a difference,the reviewers found no sign that these differences wouldhave any noticeable effect on health.4 The simplistic claim that organic food is more nutritious than conventional food was always likely to be misleading. Food is a natural product,and the health value of different foods will vary for a number of rea- sons,including freshness,the way the food is cooked,the type of soil it is grown in,the amount of sunlight and rain crops have received,and so'on.Likewise,the flavour of a carrot has less to do with whether it was fertilised with manure（粪便）or something out of a plastic sack than with the variety of carrot and how long ago it was dug up.5 The notion that organic food is safer than"normal"food is also contradicted by the fact that many of our most common foods are full of natural toxins（毒素）.As one research expert says: "People think that the more natural something is,the better it is for them.That is simply not the case.In fact,it is the opposite that is true:the closer a plant is to its natural state,the more likely it is that it will poison you.Naturally, many plants do not want to be eaten,so we have spent 10,000 years developing agriculture and breeding out harmful traits from crops."Techniques of organic farming help_________.A:affect their nutritional contentB:poison youC:improve soil qualityD:be eatenE:show that organic crops are safer than conventional onesF:be soeciallv trained
考题
毒物在体内的蓄积量主要受哪些因素的影响（）A、毒性、摄入量、生物半减期B、摄入量、生物半减期和作用时间C、理化特性、毒性、摄入量D、摄入量、理化特性、作用时间E、蓄积部位、摄入量、生物半减期
考题
自由基具有以下特性（）A、奇数电子，低化学活度，生物半减期极短，有顺磁性B、奇数电子，高化学活度，生物半减期极短，有顺磁性C、奇数电子，低化学活度，生物半减期极长，有顺磁性D、奇数电子，高化学活度，生物半减期极长，有顺磁性
考题
单选题自由基具有以下特性（）A
奇数电子，低化学活度，生物半减期极短，有顺磁性B
奇数电子，高化学活度，生物半减期极短，有顺磁性C
奇数电子，低化学活度，生物半减期极长，有顺磁性D
奇数电子，高化学活度，生物半减期极长，有顺磁性
考题
单选题自由基具有下列哪种特性（）。A
奇数电子，高化学活性，半减期极短，无顺磁性B
奇数电子，低化学活性，半减期极短，有顺磁性C
奇数电子，高化学活性，半减期极短，有顺磁性D
奇数电子，低化学活性，半减期极长，有顺磁性E
奇数电子，高化学活性，半减期极长，有顺磁性
考题
名词解释题土壤有机持分解率 decomposition rate of soil organic matter
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