Dietary intake of zinc in the population of JiangsuProvince, China

忘记吃过主食导致肥胖的英语阅读理解Like a needle climbing up a bathroom scale, the number keeps rising. In 1991, 15% of Americans were obese(肥胖的); by 1999, that proportion had grown to 27%. Youngsters, who should have age and activity on their side, are growing larger as well: 19% of Americans under 17 are obese. Waistbands have been popping in other western countries too, as physical activity has declined and diets have expanded. By and large, people in the rich world seem to have lost the fight against flab(松弛).Meanwhile, poorer nations have enjoyed some success in their battles against malnutrition and famine. But, according to research presented at the annual meeting of the American Association for the Advancement of Science, it is more a case of being out of the frying pan and into the fire. The most striking example actually in the poor world comes from the Pacific islands, home of the world's most obese communities. In 1966, 14% of the men on this island were obese while 100% of men under the age of 30 in 1996 were obese.This increase in weight has been uneven as well as fast. As a result, undernourished and over-nourished people frequently live cheek by jowl(面颊). The mix can even occur within a single household. A study of families in Indonesia found that nearly 10% contained both the hungry and the fat. This is a mysterious phenomenon, but might have something to do with people of different ages being given different amounts of food to eat.The prospect of heading off these problems is bleak. In many affected countries there are cultural factorsto contend with, such as an emphasis on eating large meals together, or on food as a form. of hospitality.Moreover, there is a good measure of disbelief on the part of policymakers that such a problem Could existin their countries. Add to that reluctance on the part of governments to spend resources on promoting dietand exercise while starvation is still a real threat, and the result is a recipe for inaction. Unless something is done soon, it might not be possible to turn the clock back.Choose correct answers to the question:1.The first sentence of the passage most probably implies that______.A.many Americans are obsessed with the rising temperature in their bathroomB.more people are overweighed in the United StatesC.people are doing more physical exercises with the help of scalesD.youngsters become taller and healthier thanks to more activities2.As physical exercise declines and diet expands, ______.A.other western countries has been defeated by fatB.obesity has become an epidemic(流行病)of the rich worldC.waistbands begin to be popular in other western countriesD.western countries can no longer fight against obesity3.Which is NOT the point of the example of the Pacific Islands?A.The poor community has shaken off poverty and people are well-fed now.B.Obesity is becoming a problem in the developing world too.C.Excessive weight increase will cause no less harm than the food shortage.D.The problem of overweight emerges very fast.4.Of tackling obesity in the poor world, we can learn from the passage that____A.the matter is so complex as to go beyond our capacityB.no matter what we do, the prospect will always be bleakC.it is starvation, the real threat, that needs to be solvedD.we should take immediate actions before it becomes incurable5.What is the main idea of this passage?A.Obesity is now a global problem that needs tackling.B.The weights increase fast throughout the whole world.C.Obesity and starvation are two main problems in the poor world.D.Obesity has shifted from the rich world to the poor world.。

收稿日期:2017-09-25作者简介:康杰,男,美国运动医学院院士。

主要研究方向:运动中生物能代谢、运动营养补剂评论、有氧和抗阻训练的生理学适应、运动处方优化。

E-mail:kang@。

作者单位:1.美国新泽西大学健康与运动科学学院人体机能实验室。

2.上海交通大学医学院附属瑞金医院高血压研究所,上海200025。

生酮饮食对体重管理、肌肉合成以及运动表现的影响康杰(美)12译近年来,大量文献报道极低碳水化合物生酮饮食在许多疾病起到治疗作用,这类饮食可以导致称为酮症的特殊代谢状态。

生酮饮食应用在癫痫治疗中已有数十年历史[1],而在20世纪70年代,这类饮食因可以减轻体重而被广泛知晓,特别是著名的“阿特金斯饮食法”[2]。

最近,生酮饮食在治疗其他Dur ing recent years,an increasing amount of evi-dence has accumulated in the literature,suggesting thatvery-low-carbohydrate ketogenic diets could have atherapeutic role in numerous diseases.These types ofdiets result in a metabolic state of ketosis.The use ofketogenic diets in treating epilepsy has been well estab-疾病的研究中也取得了较好的结果,鉴于目前美国每年的医药费用达到7500亿美元[3],如果饮食干预可以减少对药物使用的依赖,它将带来显著的社会以及经济效益,这也将成为今后一个重要的研究方向。

最近生酮饮食疗法也在许多运动项目中流行,希望通过生酮饮食疗法减轻体重,获得更好的运动表现。

然而,生酮饮食对提高运动表现是否有功效并没有得到一致的认可。

2024年小学3年级上册英语第一单元全练全测(含答案)考试时间：80分钟（总分:100）B卷考试人：_________题号一二三四五总分得分一、综合题(共计100题)1、听力题：The boy plays the ________.2、What is the opposite of 'hot'?a. Warmb. Coolc. Coldd. Mild答案:c3、听力题：My favorite subject is ________.4、填空题：My dog is very _________ to me. (忠诚)5、填空题：She is a musician, ______ (她是一位音乐家), and plays the piano.6、What do we call the main character in a story?a. Protagonistb. Antagonistc. Supporting characterd. Villain答案:a7、填空题：My favorite thing to do with my friends is ______.8、Which month comes after June?A. MayB. JulyC. AugustD. September答案: B9、Which fruit is known for having seeds on the outside?A. BananaB. StrawberryC. AppleD. Peach答案:B10、填空题：The ________ (生态旅游) promotes conservation.11、填空题：My friend is my best _______ who always supports me.12、填空题：The simplest form of matter is called an _______. (元素)13、What is the name of the famous playwright who wrote "Hamlet"?A. William ShakespeareB. Anton ChekhovC. Tennessee WilliamsD. Arthur Miller答案: A14、What do you call a person who performs magic tricks?A. IllusionistB. MagicianC. WizardD. Enchanter答案:B15、What do we call a baby cat?A. PupB. KittenC. CalfD. Chick答案:B16、填空题：I think kindness is the best _______ (礼物) we can give. It costs nothing but means everything.17、What is the process of a caterpillar becoming a butterfly called?A. MetamorphosisB. EvolutionC. TransformationD. Development18、填空题：In the future, I hope to design toys that are both ________ (形容词) and educational.19、听力题：The chemical symbol for chromium is _______.20、What is the largest mammal in the world?A. ElephantB. Blue WhaleC. GiraffeD. Hippopotamus21、填空题：The __________ (历史的探索) is an ongoing journey.22、What is the process of making bread called?A. BakingB. FryingC. BoilingD. Grilling答案:A. Baking23、填空题：The ________ (小溪) runs through our backyard.24、听力题：The chemical formula for ammonium sulfate is __________.25、The Great Wall of China was built to:A. Keep out animalsB. Protect against invasionsC. Mark boundariesD. Serve as a road答案:B26、听力题：He ___ (runs) every day.27、填空题：The _____ (植物教育课程) can inspire future botanists.28、填空题：A _____ (水果) tree takes years to mature.29、What is the term for the change of state from liquid to gas?A. FreezingB. MeltingC. CondensationD. Evaporation答案: D30、填空题：I enjoy ________ (走路) in the park.31、What is the capital of Armenia?A. YerevanB. GyumriC. VanadzorD. Artashat答案:A32、听力题：The cat is hiding _____ (under/above) the table.33、听力题：She is _____ (dancing) at the event.34、How many zeros are in one hundred?A. 1B. 2C. 3D. 4答案:B35、听力题：The _______ can help reduce stress and anxiety.36、听力题：The capital of Faroe Islands is __________.37、What is a baby sheep called?A. CalfB. KittenC. LambD. Puppy答案:C38、What type of animal is a frog?A. MammalB. ReptileC. AmphibianD. Bird39、填空题：The ________ was a defining battle in the history of modern warfare.40、听力题：The chemical formula for bismuth trioxide is _______.41、听力题：Chemical reactions can be influenced by temperature and _____.42、What is the name of the famous sculpture by Michelangelo?A. DavidB. The ThinkerC. The KissD. Venus de Milo答案: A. David43、填空题：I can ______ (游泳) in the lake.44、填空题：The country known for its deserts is ________ (沙特阿拉伯).45、填空题：My friend has a pet _______ (鹦鹉) that can talk!46、填空题：My _____ (外婆) tells great stories.47、听力题：My favorite color is _____ (蓝色).48、听力题：I like to __________ in the pool.49、听力题：The ant builds intricate _____.50、填空题：A _____ is a large area of flat land that is often flooded.51、What do we call the person who helps us when we are sick?A. TeacherB. DoctorC. NurseD. Chef52、听力题：The dog is ________ in the grass.53、填空题：The __________ is a famous mountain range in Italy. (阿尔卑斯山)54、What is the name of the fairy tale character who lost her glass slipper?A. Snow WhiteB. CinderellaC. RapunzelD. Little Red Riding Hood答案:B55、听力题：A saturated solution can be created by adding solute until no more can be ______.56、填空题：The _____ (小海豚) leaps out of the water in joy. 小海豚高高跃出水面，欢快无比。

节约粮食的倡议书英语考研Ladies and gentlemen,I am here today to address an increasingly pressing concern - the need to conserve food resources. As the global population continues to soar, the demand for food is at an all-time high. However, our limited resources are being stretched to their limits, and it is crucial that we take immediate action to reduce food waste and promote sustainable practices.Firstly, it is important to raise awareness about the impact of food waste on our environment. Not only does the production of food emit greenhouse gases, contributing to climate change, but it also wastes valuable land, water, and energy resources. By throwing away uneaten food, we are essentially discarding all the resources that went into its production. Through education and outreach programs, we can highlight the environmental consequences of food waste and inspire individuals to make conscious choices.Additionally, it is imperative that we adopt sustainable agricultural practices to maximize food production and minimize waste. This includes investing in advanced farming technologies that improve efficiency and reduce the need for pesticide and fertilizer use. Furthermore, promoting organic farming practices and supporting small-scale farmers can aid in reducing food waste as they tend to be more mindful of resource conservation. By encouraging sustainable farming methods, we can ensure a more abundant and equitable distribution of food resources.Furthermore, we must encourage responsible consumption habitsamong individuals. This can be achieved by promoting meal planning and portion control, which not only reduce food waste but also promote healthier eating habits. We should also encourage the utilization of leftover food through creative recipes and techniques. By fostering a culture of responsible consumption, we can significantly reduce the amount of food wasted on a daily basis.Lastly, collaboration between governments, businesses, and individuals is crucial to combat food waste. Governments can implement policies and regulations that promote sustainable agriculture and facilitate the redistribution of surplus food to vulnerable populations. Businesses have a role to play by adopting sustainable packaging practices and by partnering with food banks and non-profit organizations to minimize food waste. Furthermore, individuals can make a difference by supporting local food drives and community initiatives that aim to reduce food waste.In conclusion, conserving food resources is an urgent necessity that requires collective action. By raising awareness, adopting sustainable agricultural practices, encouraging responsible consumption habits, and fostering collaboration, we can make significant strides towards a more sustainable and equitable future. Let us work together to eliminate food waste and ensure that our precious resources are used efficiently for generations to come.。

The Chinese diet is renowned for its rich variety and deep cultural roots.It is characterized by a balance of flavors,textures,and colors,reflecting the harmony and diversity of Chinese culture.Here are some key aspects of the Chinese diet that make it unique and appealing:1.Diversity of Ingredients:Chinese cuisine uses a wide range of ingredients,including various types of grains,vegetables,fruits,meats,and seafood.This diversity ensures a balanced intake of nutrients and a variety of flavors in every meal.2.Balance of Flavors:Chinese dishes often strive for a balance of the five basic tastes: sweet,sour,bitter,spicy,and salty.This balance is achieved through the careful selection and combination of ingredients and seasonings.e of Spices and Herbs:Chinese cooking employs a variety of spices and herbs,such as ginger,garlic,star anise,and Sichuan peppercorns,which not only add flavor but also have health benefits.4.Cooking Techniques:The Chinese diet features a multitude of cooking methods, including stirfrying,steaming,boiling,braising,and deepfrying.Each technique is chosen to best preserve the natural flavors and nutritional value of the ingredients.5.Emphasis on Whole Grains:Whole grains like rice,wheat,and millet are staples in Chinese meals.They provide a good source of energy and are rich in fiber,vitamins,and minerals.6.Plenty of Vegetables:Chinese meals typically include a generous serving of vegetables, which are often stirfried,steamed,or used in soups.This ensures a high intake of vitamins,minerals,and antioxidants.7.Moderation in Meat Consumption:While meat is a part of the Chinese diet,it is often consumed in moderation,with more emphasis on plantbased foods.This approach aligns with modern dietary recommendations for a healthy lifestyle.8.Inclusion of Tofu and Soy Products:Tofu and other soy products are common in Chinese cuisine,providing a good source of protein for vegetarians and a healthy alternative to meat.9.Tea Culture:Tea is an integral part of the Chinese diet and is consumed throughout the day.It is not only a beverage but also a part of social and medicinal practices.10.Seasonal Eating:The Chinese diet often follows the principle of eating according to the seasons,believing that certain foods are more beneficial when consumed at their peak growing times.11.Health and Wellness:Traditional Chinese Medicine TCM principles often guide dietary choices,with an emphasis on foods that are believed to promote health and prevent disease.12.Culinary Traditions:Each region in China has its own unique dishes and culinary traditions,which are passed down through generations and reflect the local culture and climate.The Chinese diet is a testament to the countrys rich history and cultural heritage.It offers a wealth of flavors and health benefits,making it an attractive and nutritious choice for people around the world.。

D12492⾼脂饲料简介D12492 ⾼脂饲料简介Research Diets公司是⼀家专业⽣产科研实验室动物饲料的⼤型公司，是包括脂肪热能的颗粒饲料及各种维⽣素缺乏饲料的著名专业供应商.近年中国科研单位使⽤D12492这款⾼脂饲料正以数倍增长。

上海华雅思创⽣物仓库备有现货，希望能够帮助更多的科研使⽤者减少订购期货的时间，⼀般从国外发货正常要4周时间，但是如果有现货，⼀般2-3天就可以到货了，这样就⼤⼤的减少了运输时间。

特别推荐介绍①货号D12451：Rodent Diet with 45 kcal% Fat，45%脂肪热能的啮齿动物饲料；②货号D12492：Rodent Diet with 60 kcal% Fat，60%脂肪热能的啮齿动物饲料；配⽅成分：Casein lactic酪蛋⽩、L-Cystine胱氨、Corn Starch⽟⽶淀粉、Maltodextrin 麦芽糊精、Sucrose蔗糖、Cellulose BW200纤维素、Soybean Oil⾖油、Lard 猪油、Mineral Mix S10026*复合矿物质、DiCalcium Phosphate 磷酸氢钙、Calcium Carbonate 碳酸钙、Potassium Citrate(1 H2O)柠檬酸钾、Vitamin Mix V10001* 复合维⽣素、Choline Bitartrate酒⽯酸氢胆碱。

The "Original" High Fat DietIn 1996, a regular customer of Research Diets, Inc. approached Dr. Ulman to help formulate an OpenSource Diet to use in a Diet Induced Obesity (DIO) mouse model. The model was based loosely on published work by (1) Surwit et al.(1995) and (2) West et al. (1995), in which a chow-based, undefined diets were used to study the DIO phenotype in inbred mouse strains. However, the group required a diet with a defined, flexible formulation containing 45 kcal% fat, predominantly lard, and the product needed to be a solid pellet in order to conduct food intake studies.Research Diets, Inc. submitted several preliminary formulas for discussion, and the group settled on D12451 (HFD) and its' control OpenSource Diet, D12450 (LFD).The publication of the discovery of leptin by (3) Zhang and Friedman et al (1994) created worldwide interest in this novel peptide as a tool for research and therapeutic discovery for obesity and its related disorders. D12451 not only generated the hypothesized phenotype in itsfirst study, it also helped the investigators discover, research, and describe the leptin resistance phenomenon. The results of this initial study, and the description of the use of these two diets are presented in the paper by (4) Van Heek et al (1997),“Diet induced obese mice developperipheral, but not central resistance to leptin”.The D12492 StoryOn April 19th 1999, nearly 15 years after Research Diets, Inc. began in Dr. Ed Ulman's kitchen, John Larose made the first 25 kg of D12492 (VHFD). Somehow, he was able to pellet 12.5 kg of this 60 kcal % high fat diet and on April 22, 1999 the first box of pelleted D12492 was shipped. In 1999 research Diets shipped 150 kg of D12492, and today ship over 10,000 kg ofD12492 monthly. Today, there are more DIO rodent models made using our diets than any other diets in the world. This year celebrates the 10th anniversary of D12492.WorldwideD12492 has shipped to 1000s of individuals, working at 420 separate institutions in 33 countries (Australia, Belgium, Canada, Chile, China, Colombia, Czech Republic, Denmark, Finland, France, Germany, Hungary, India, Ireland, Israel, Italy, Japan, Mexico, Netherlands, New Zealand, Norway, Poland, Portugal, Scotland, Singapore, South Korea, Spain, Sweden, Switzerland, Turkey, United Kingdom, and United States).How Many Mice Eat D12492?Considering D12492 production in terms of mice eating and assuming mice eat 5 gm of D12492/day, 250,000+ kg of D12492 could feed 50 million mice for 1 day. This means that 250,000 or so mice could be observed for 200 days each while eatingD12492. With 8000+ kg of D12492 shipping monthly (averaging 265 kg each day) we can estimate that somewhere and everywhere in the world today there are 50,000 mice alive and growing fat while eating our D12492.What It MeansObservations made with these 50,000 mice can be compared to each other and to the 250,000 or so other mice that alreadyate D12492 and were observed, recorded and reported by someone, somehow, somewhere, so far.Over the past 10 years, these diets, have become the standard for researchin the field of obesity, diabetes, and metabolic syndrome. Top worldwide breeders CRL, Taconic and JAX, feed D12492 to produce DIO mice for the research community.A recent search revealed hundreds of publications in which these diets were utilized. By using these standards, investigators are privy to a wide range of reference data from an expanding research publication base.P.S. D12492 is only 1 of the 14,000 diets we’ve formulated and produced and there’smore every day.A Word of Caution Don’t be misled by diet manufacturers who claim to offer the same OpenSource diet formulas as Research Diets, Inc. Though it is true that all our formulas are open, there may be differences in the sources of ingredients or the vitamin and mineral mixes used to produce the diet.There is only one sure way to repeat research based on the "Original" OpenSource Diet formula—go to the source of that formula. There is only one place to get OpenSource Diets and that’s at Research Diets, Inc.References:1. Surwit, R.S., M.N. Feinglos, J. Rodin, A. Sutherland, A.E. Petro, E.C. Opara,C.M. Kuhn, and M. Rebuffe-Scrive. 1995. Differential effects of fat and sucrose on the development of obesity and diabetes in C57BL/6J and A/J mice. Metab. Clin. Exp. 44:645-651.2. West, D.B., J. Waguespack, and S. McCollister. 1995. Dietary obesity in the mouse: interaction of strain and diet composition. Am. J. Physiol. 268:R658-R665.3. Zhang, Y., R. Proenca, M. Maffei, M. Barone, and J.M. Friedman. 1994. Positional cloning of the mouse obese gene and its human homologue . Nature (Lond.). 372:425-431.4.Van Heek, M., D.S. Compton, C.F. France, R.P. Tedesco, A.B. Fawzi, M.P. Graziano, E.J. Sybertz, C.D. Strader, and H.R. Davis. 1997. Diet induced obese mice develop peripheral, but not central resistance to leptin”. J. Clin. Invest. 99:385-390.D12492Product DataDescriptionRodent Diet with 60% kcal% fat.Used in ResearchObesityDiabetesPackagingProduct is packed in 12.5 kg box.Each box is identified with theproduct name, description, lotnumber and expiration date.Lead TimeIN-STOCK. Ready for next day shipment.Gamma-IrradiationYes. Add 10 days to delivery time. FormPellet, Powder, LiquidShelf LifeMost diets require storage in a cool dry environment. Stored correctly they should last 3-6 months. Because of the high fat content is best if kept frozen.Control DietsD12450B本⽂原创。

Regulation of the Epigenome by Vitamin CJuan I.Young,1,2Stephan Z ¨uchner,1,2and Gaofeng Wang 1,2,3,∗1John P.Hussman Institute for Human Genomics,2Dr.John T.Macdonald FoundationDepartment of Human Genetics,and 3Bascom Palmer Eye Institute,University of Miami Miller School of Medicine,Miami,Florida 33136;email:gwang@Annu.Rev.Nutr.2015.35:545–64First published online as a Review in Advance on May 6,2015The Annual Review of Nutrition is online at This article’s doi:10.1146/annurev-nutr-071714-034228Copyright c2015by Annual Reviews.All rights reserved∗Corresponding authorKeywordsvitamin C,iron-and 2-oxoglutarate-dependent dioxygenase,Ten-eleven translocation dioxygenase,JmjC-domain-containing histone demethylase,DNA demethylation,histone demethylationAbstractEmerging evidence suggests that ascorbate,the dominant form of vitamin C under physiological pH conditions,influences activity of the genome via regulating epigenomic processes.Ascorbate serves as a cofactor for Ten-eleven translocation (TET)dioxygenases that catalyze the oxidation of 5-methylcytosine (5mC)into 5-hydroxymethylcytosine (5hmC),and fur-ther to 5-formylcytosine (5fC)and to 5-carboxylcytosine (5caC),which are ultimately replaced by unmodified cytosine.The Jumonji C (JmjC)-domain-containing histone demethylases also require ascorbate as a cofactor for his-tone demethylation.Thus,by primarily participating in the demethylation of both DNA and histones,ascorbate appears to be a mediator of the in-terface between the genome and environment.Furthermore,redox status has a profound impact on the bioavailability of ascorbate in the nucleus.In order to bridge the gap between redox biology and genomics,we suggest an interdisciplinary research field that can be termed redox genomics to study dynamic redox processes in health and diseases.This review examines the evidence and potential molecular mechanism of ascorbate in the demethyla-tion of the genome,and it highlights potential epigenetic roles of ascorbate in various diseases.A n n u . R e v . N u t r . 2015.35:545-564. D o w n l o a d e d f r o m w w w .a n n u a l r e v i e w s .o r g A c c e s s p r o v i d e d b y N o r t h w e s t A g r i c u l t u r e a n d F o r e s t r y U n i v e r s i t y o n 03/10/16. F o r p e r s o n a l u s e o n l y .Click here for quick links to Annual Reviews content online, including:• Other articles in this volume • Top cited articles• Top downloaded articles • Our comprehensive searchFurtherANNUAL REVIEWSContentsINTRODUCTION...............................................................546VITAMIN C AND DNA DEMETHYLATION...................................547Ten-Eleven Translocation Dioxygenases Are Fe 2+-and 2OG-Dependent Dioxygenases ..........................................547Vitamin C:An Additional Cofactor for TET Dioxygenases.......................549Vitamin C,DNA Demethylation,and Epigenetic Reprogramming................551Vitamin C and the Loss of 5hmC in Cancer......................................552Vitamin C and Peripheral Neuropathy...........................................554VITAMIN C AND HISTONE DEMETHYLATION .............................555Histone Demethylation.........................................................555Vitamin C:An Additional Cofactor for Jumonji C-Domain-ContainingHistone Demethylases.......................................................556Vitamin C,Histone Demethylation,and Epigenetic Reprogramming .............557CELLULAR AVAILABILITY OF VITAMIN C AND REDOX GENOMICS......557CONCLUSIONS.................................................................558INTRODUCTIONVitamin C (L-ascorbic acid)is an essential,water-soluble micronutrient that exists predominantly as the ascorbate anion under physiological pH conditions.It is well established that ascorbate is an antioxidant and free radical scavenger as well as an essential cofactor in numerous enzymatic reactions.Most mammals,such as rodents,synthesize ascorbate de novo in the liver from glucose through a biosynthetic pathway.In contrast,humans—as well as primates,guinea pigs,and fruit bats—no longer can synthesize ascorbate due to a mutant and nonfunctional enzyme,L-gulonolactone oxidase (Gulo),which catalyzes the last step of ascorbate biosynthesis (50).For these mammalian species,ascorbate is a vitamin that needs to be supplied through dietary sources and supplements.Ascorbate,derived from either dietary sources or the liver,enters cells primarily through sodium-dependent vitamin C transporters (SVCTs).The high-capacity,low-affinity SVCT1is primarily responsible for ascorbate absorption and reabsorption in intestinal and renal epithelial cells.The high-affinity,low-capacity SVCT2distributes ascorbate to most tissues and is expressed more ubiquitously (91).The average concentration of ascorbate in the plasma of healthy humans or mice is ∼50μM.Plasma ascorbate concentration below 11.4μM is conventionally considered deficient and is associated with a risk of developing scurvy.Currently,the recommended dietary allowances by the Institute of Medicine are 90mg ascorbate for adult males and 75mg for adult females,although the tolerable upper intake level for adults is 2,000mg per day.The daily adequate intake for infants (0–12months)is ∼40–50mg.After ascorbate is transported across the plasma membrane,it accumulates within cells,and its intracellular concentration can reach ∼1–10mM (58).Thus,the majority of mammalian cells maintain highly elevated intracellular ascorbate concentrations compared to the extracellular milieu.For instance,neurons could have up to 10mM of intracellular ascorbate,which is about 200times higher than the extracellular ascorbate concentration (73).Ascorbate is a relatively mild reducer and antioxidant.After a cascade of two-round oxida-tion and the loss of two electrons,the oxidized form of vitamin C,termed dehydroascorbic acidA n n u . R e v . N u t r . 2015.35:545-564. D o w n l o a d e d f r o m w w w .a n n u a l r e v i e w s .o r g A c c e s s p r o v i d e d b y N o r t h w e s t A g r i c u l t u r e a n d F o r e s t r y U n i v e r s i t y o n 03/10/16. F o r p e r s o n a l u s e o n l y .(DHA),is formed.Instead of utilizing SVCTs,DHA enters and leaves cells via facilitated glucose transporters.Once inside the cell,DHA can be rapidly reduced back to ascorbate.However,the reduced ascorbate is dominant,and DHA is barely detectable in the plasma of healthy humans (43),suggesting that most cells take up and accumulate ascorbate primarily through SVCTs.During evolution,primates and some other species lost the ability to synthesize ascorbate due to accumulation of mutations in the Gulo gene.The antioxidant function of ascorbate generally appears to be compensated for by alternative reducing systems in these species (54).However,its role as a cofactor for iron-and 2-oxoglutarate-dependent dioxygenases is irreplaceable,as primates and some other species develop scurvy,osteoporosis,and other disease phenotypes unless provided with adequate dietary ascorbate.The iron-and 2-oxoglutarate (2OG,also known as α-ketoglutarate)-dependent dioxygenases utilize Fe 2+as a cofactor and 2OG as a cosubstrate;additionally,some of them require ascorbate as another cofactor for full catalytic activity (59).One classic member of this family is collagen prolyl 4-hydroxylase (P4H),which is well known for its involvement in scurvy.In the absence of ascorbate,the initial hydroxylation catalyzed by collagen P4H can proceed at a maximal rate.However,the catalytically inactive oxidized iron species (mostly Fe 3+)soon inactivates collagen P4H,which leads to an incomplete hydroxylation of proline residues in collagen and ultimately the characteristic signs of scurvy (23).When available,ascorbate has the capacity to reduce oxidized iron species to catalytically active Fe 2+.Ascorbate thus assists collagen P4H to complete the hydroxylation and prevent scurvy.Overall,it has been well established that ascorbate is required to maintain a number of Fe 2+-and 2OG-dependent dioxygenases in their fully active forms (59).In recent years,tremendous progress has been made in the identification of a number of novel Fe 2+-and 2OG-dependent dioxygenases that catalyze the hydroxylation of methylated nucleic acids (DNA and RNA)and methylated histones.DNA and histone methylation are the major epigenetic hallmarks in the mammalian genome.It has also been shown that some of these nuclear dioxygenases require ascorbate as a cofactor to start and complete both DNA demethylation and histone demethylation processes.These unexpected findings have uncovered a previously unknown function of ascorbate in regulating the epigenome,which calls for a reevaluation of the role of ascorbate in human health and diseases.VITAMIN C AND DNA DEMETHYLATION Ten-Eleven Translocation Dioxygenases Are Fe 2+-and 2OG-Dependent DioxygenasesThe epigenome reflects the interface of a dynamic environment and the genome.Known epige-netic events include covalent modifications of nucleotides and histones,chromatin remodeling,and noncoding RNAs,which collectively constitute the epigenome.Methylation at the C 5po-sition of cytosine [5-methylcytosine (5mC)]is the major and best-characterized epigenetic mark of mammalian DNA.The transfer of a methyl group from the donor S -adenosylmethionine to a cytosine is catalyzed by DNA methyltransferases (DNMTs),which are regarded as the writers of this epigenetic mark.After the methylation is completed,5mC,especially in CpG dinucleotide context,can be recognized and then bound with a group of methyl-CpG-binding proteins.As readers,these methyl-CpG-binding proteins then mediate multiple functions,such as regulat-ing transcription,initiating chromatin remodeling,and maintaining genome stability and cellular identity.Although 5mC is a relatively stable epigenetic mark,it can be lost by passive dilution via a lack of maintenance by DNMT1during DNA replication,which would result in passive demethy-lation.Until a few years ago,it had remained largely unclear whether and how the methyl groupA n n u . 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F o r p e r s o n a l u s e o n l y .in 5mC could be actively removed.The key question was whether DNA demethylases functioned as erasers to catalyze the removal of the methyl group from 5mC.In 2009,Kriaucionis &Heintz (44)reported the presence of an unusual DNA nucleotide,5-hydroxymethylcytosine (5hmC),in the mouse brain.Although 5hmC constitutes less than 1%of total nucleotides,its percentage was higher in cerebellar Purkinje neurons than in granule cells.In contrast,there was no difference in 5mC content between these two distinct neuronal cell types.Interestingly,transcriptionally active euchromatin was enriched in Purkinje neurons,whereas granule cells contained more of the transcriptionally inactive heterochromatin.On the basis of these results,Kriaucionis &Heintz (44)suggested that 5hmC might play a role in the epigenetic regulation of neuronal functions.Interestingly,it appears that this was not the first time that 5hmC was identified in a genome.As early as 1952,5hmC was detected in T-even bacteriophages (93).It was discovered that 5hmC could be incorporated into the viral genome to resist the attack of restriction enzymes from the bacteria.In 1972,5hmC was also identified in mammalian DNA (70).However,5hmC was generally regarded as oxidatively damaged cytosine in the mammalian genome that might eventually be replaced by DNA repair mechanisms.After 1972,not much attention was given to 5hmC in terms of elucidating its possible physiological functions in the genome until the Kriaucionis &Heintz report spurred new interest.The breakthrough in understanding the presence of 5hmC in the genome came from studies of a gene family known as Ten-eleven translocation (TET ).TET1at chromosome 10q22was originally named after the discovery that this gene fused with the mixed-lineage leukemia (MLL )gene resulting from a chromosome translocation of 10q22and 11q23in acute myeloid leukemia (51).TET1appears to be a member of a well-conserved gene family that contains two other members (TET2at 4q24and TET3at 2p12)in the human genome.Soon after this breakthrough,somatic mutations in TET2were identified in about 15%of patients affected by myeloid leukemia (12).However,the way in which the mutant TETs contributed to myeloid leukemia was unclear.As a matter of fact,the basic biological function of TETs was unknown at that time.Through a series of elegant experiments,Rao’s lab (85)demonstrated for the first time that TET1enzymatic activity involved the oxidation of 5mC to 5hmC,providing the first bona fide active demethylation of DNA.Via bioinformatics approaches,TET dioxygenases were identified as mammalian homologs of the proteins JBP1and JBP2in trypanosome,a unicellular protozoon.These two proteins were known to oxidize the 5-methyl group of thymine.Upon forced expression of wild-type (WT)and mutant TET1in cultured cells,a dramatic reduction of the 5mC signal was observed in WT but not mutant TET1-overexpressing cells.In vitro enzymatic analysis further demonstrated that the recombinant TET1catalytic domain catalyzed 5mC to 5hmC in methylated DNA fragments (85).Both JBP1and JBP2belong to the Fe 2+-and 2OG-dependent dioxygenases family,suggesting that the enzymatic activity of TET dioxygenases may also depend on Fe 2+and 2OG.Indeed,withdrawing 2OG from the in vitro reaction almost completely blocked the conversion of 5mC to 5hmC.Furthermore,removing Fe 2+dramatically inhibited the conversion but did not abolish it completely.The explanation for this result was that a certain amount of Fe 2+might be contained in the recombinant TET1catalytic domain during the protein purification process.Thus,TET1was identified as a Fe 2+-and 2OG-dependent enzyme that converts 5mC to 5hmC.In 2010,mouse TETs,including TET1,TET2,and TET3,were also identified as being able to oxidize 5mC to 5hmC (34).Subsequent experiments further confirmed that TETs are Fe 2+-and 2OG-dependent dioxy-genases.First,the binding motif of Fe 2+in TETs includes at least two histidine residues and one asparagine residue,which are conserved across JBP1,JBP2,human TETs,and mouse TETs (78).Mutations at the Fe 2+-binding sites in TET dioxygenases diminished the 5hmC signal in the cultured cells (34).Second,2OG is a critical intermediate metabolite of the Krebs cycle.TheA n n u . 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F o r p e r s o n a l u s e o n l y .oxidative decarboxylation of isocitrate to 2OG is catalyzed by enzymes that are termed isocitrate dehydrogenases (IDHs).Mutations in IDH1and IDH2have been associated with certain can-cers in which 5hmC is depleted.Instead of 2OG,the mutant IDH produces 2-hydroxyglutarate (2HG),which is also correlated with the reduction of 5hmC in cancers (94).In cultured cells,supplementation of 2HG suppressed the conversion of 5mC to 5hmC,suggesting that 2HG is an inhibitor of 2OG competing for the binding site in TET dioxygenases (94).These lines of evidence have demonstrated that similarly to P4H,the catalytic activity of TET dioxygenases is indeed dependent on Fe 2+and 2OG.The Zhang group demonstrated that TETs further oxidize 5hmC to 5-formylcytosine (5fC)and 5-carboxylcytosine (5caC)(35).Both 5fC and 5caC could be excised by the DNA repair enzyme thymine-DNA glycosylase (TDG)to produce an abasic position,which is eventually re-placed by an unmodified C as shown primarily by two groups of investigators (29,53).Thus,5hmC,5fC,and 5caC have been proposed as demethylation intermediates.So far,our knowledge of TETs-mediated DNA demethylation is the following:The Fe 2+-and 2OG-dependent TETs consecutively oxide 5mC to 5hmC,then to 5fC and 5caC,which can eventually be removed from the genome and substituted by unmodified C,thus completing the process of DNA demethy-lation.Although it involves multiple steps,the TET-mediated oxidation,combined with base excision repair,constitutes the most important and consistent pathway responsible for the active demethylation of DNA.Vitamin C:An Additional Cofactor for TET DioxygenasesThe requirement for ascorbate as an additional cofactor for P4H and other dioxygenases suggested a potential role for this reducing cofactor in TET-mediated DNA demethylation.Interestingly,studies have shown that ascorbate has the capacity to modify the status of DNA methylation in mammalian cells.For instance,ascorbate causes the widespread DNA demethylation of nearly 2,000genes in embryonic stem cells (11).Ascorbate also enhances the generation of induced pluripotent stem cells (iPSCs)from terminally differentiated cells,which is usually accompanied by genome-wide DNA demethylation (18,84).These results indicate that ascorbate could be involved in the DNA demethylation process.However,it is unclear whether ascorbate participates directly in DNA demethylation and whether the facilitated DNA demethylation is mediated by the enhanced catalytic activity of TETs by ascorbate.Initial in vitro enzymatic analysis suggested that ascorbate was not essential for TET-mediated hydroxylation of 5mC.It was reported that in the absence of ascorbate,recombinant TET1converted 5mC to 5hmC at a similar efficiency as when ascorbate was included or excluded in the reaction (85).It is now understood that Fe 2+and 2OG could solely satisfy the need of TET dioxygenases in the short term to initiate the hydroxylation of 5mC,as they do for P4H.A possible premature exhaustion of TET enzymatic activity in the absence of ascorbate was not fully explored.It was not clear how long this reaction could last without ascorbate,especially when the in vitro stoichiometry of the reaction was not completely controlled.In some in vitro experimental settings,Fe 2+was obviously overloaded (molar ratio Fe 2+:TET1>20).In this case,Fe 2+might remain available for TET dioxygenases over short periods of time.Thus,under this condition,ascorbate is not required as a rejuvenator of TET dioxygenases via its reduction of the inactive oxidized iron species (Fe 3+)to the active Fe 2+state after TET dioxygenases have been inactivated by coupled or uncoupled decarboxylation of 2OG,as occurs in collagen P4H.In contrast,free Fe 2+is limited and stringently controlled within the cell.Therefore,these in vitro enzymatic analyses do not reflect the whole scenario of TET dioxygenases in catalyzing 5mC hydroxylation in the cell.The role of ascorbate as a potential cofactor for TET dioxygenases toA n n u . R e v . N u t r . 2015.35:545-564. D o w n l o a d e d f r o m w w w .a n n u a l r e v i e w s .o r g A c c e s s p r o v i d e d b y N o r t h w e s t A g r i c u l t u r e a n d F o r e s t r y U n i v e r s i t y o n 03/10/16. F o r p e r s o n a l u s e o n l y .sustain and complete the hydroxylation of 5mC to 5hmC was therefore not excluded by these in vitro enzymatic analyses.The Wang lab demonstrated for the first time that ascorbate enhanced 5hmC generation in vivo in cultured cells,most likely by acting as a cofactor for TET to hydroxylate 5mC (13,62).This previously unknown function of ascorbate in DNA demethylation was subsequently validated in different cell types and animal models by other groups (2,7,96).5hmC was originally thought to be detectable only in a few cell types,such as stem cells and neurons,but not in other fully differ-entiated cells.For instance,5hmC was previously reported as undetectable in cultured HEK-293cells,and it was only detectable in the cells when TETs were forcibly overexpressed (35).Wang et al.(89)found that mouse embryonic fibroblasts (MEFs)expressed TETs at low but detectable levels as previously reported (14,41),with TET3at a higher level than TET1and TET2.Thus,MEFs constituted an appropriate experimental system to analyze their enzymatic requirements in a cell-based experimental setting.Interestingly,standard cell culture media usually lack ascorbate in their formula.However,when ascorbate is available,it can effectively enter into cells via dif-ferent transporters.The content of 5hmC was extremely low in MEFs cultured in ascorbate-free medium.Additions of ascorbate in a dose-and time-dependent manner enhanced the genera-tion of 5hmC.The signal of 5hmC reached a plateau when MEFs were treated with 10μM ascorbate.Possibly due to the low expression of TETs in MEFs,ascorbate at a relatively low level could fulfill the requirement of TET dioxygenases to reach their maximal enzymatic activity.Surprisingly,the effect of ascorbate on 5hmC was quite rapid.The generation of 5hmC in MEFs could be induced by ascorbate in as little as one hour.The rapid effect suggested that no protein synthesis was required;rather,activation of existing TET dioxygenases was enough to generate 5hmC (62).Indeed,ascorbate treatment did not change the expression of either TETs or IDHs.It was then tested whether ascorbate works as a cofactor for TET to enhance the conversion of 5mC to 5hmC in the following cell-based experiments.(a )Treatment with other reducers such as glutathione did not change the level of 5hmC,suggesting that the effect of ascorbate on 5hmC could not be attributed to its role as a general reducer.(b )Knocking down the expression of TETs by short interfering RNAs largely abolished the effect of ascorbate on 5hmC,indicating that it is TET dioxygenases that mediate the action of ascorbate on 5hmC generation.(c )Ascorbate transporter inhibitors such as phloretin or sulfinpyrazone decreased the effect of ascorbate on 5hmC generation,suggesting that intracellular accumulation of ascorbate is necessary for acti-vating the catalytic activity of TET dioxygenases.(d )The presence of ascorbate at physiological concentration has been shown to enhance the uptake of iron by cells,raising the possibility that the effect of ascorbate on 5hmC might be indirect and mediated by an ascorbate-induced increase in the cellular uptake of iron (46–48).However,removing iron from the culture medium did not affect the induction of 5hmC by ascorbate,which suggests that the effect of ascorbate on 5hmC is independent of cellular uptake of iron.(e )Cells cultured with different concentrations of glucose,a major precursor of 2OG,exhibited the similar level of 5hmC in response to ascorbate treatment.These results indicate that the effect of ascorbate on 5hmC is not dependent upon iron uptake,the expression of TET and IDH,or the production of 2OG,which overall suggests that ascorbate may directly participate in the conversion of 5mC to 5hmC,most likely as a cofactor of TETs (13,62).Embryonic stem cells are generally cultured in the medium without ascorbate.The Ramalho-Santos group (2)observed that when added to medium,ascorbate led to a rapid and global increase in 5hmC,which was followed by DNA demethylation of many gene promoters and upregulation of demethylated germline genes.Yin et al.(96)reported that ascorbate directly enhanced the activity of purified C-terminal catalytic domain of TET2to oxidize 5mC to 5hmC and 5fC,whereas other reducers such as spermidine,vitamin B1,vitamin E,glutathione,nicotinamide adenine dinucleotide phosphate,and L-cysteine did not have this effect.After treatment withA n n u . 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F o r p e r s o n a l u s e o n l y .5C5caCFigure 1The role of ascorbate in DNA demethylation.As a cofactor,ascorbate participates in the cascade oxidation of 5mC to 5hmC,to 5fC,and to 5caC catalyzed by TET dioxygenases.5fC and 5caC are then replaced by unmodified 5C by base excision repair machinery.In addition,the inability to maintain 5hmC in the newly synthesized DNA leads to passive demethylation.The methylation of anunmodified 5C could be reestablished by DNMT1,thus completing a cycle of DNA methylation and demethylation.Abbreviations:5caC,5-carboxylcytosine;5fC,5-formylcytosine;5hmC,5-hydroxymethylcytosine;5mC,5-methylcytosine;BER,base excision repair;DHA,dehydroascorbic acid;DNMT,DNA methyltransferase;TET,Ten-eleven translocation.ascorbate,mouse embryonic stem cells displayed significant increases in 5mC oxidation products,particularly 5fC and 5caC.Furthermore,5hmC was decreased in various tissues in Gulo knockout mice.These results suggest that ascorbate could be a cofactor for TET in the cascade oxidation of 5mC.Chen et al.(7)reported that TET1,in an ascorbate-dependent manner,regulated 5hmC formation at loci critical for the reprogramming of iPSCs.From in vitro enzymatic activity analysis to cell-and animal-based experiments,the available evidence strongly suggests that ascorbate is a cofactor for TET dioxygenases in the conversion of 5mC to 5hmC,and further to 5fC and to 5caC,thus modulating DNA demethylation (Figure 1).Vitamin C,DNA Demethylation,and Epigenetic ReprogrammingThe amount of ascorbate needed for TETs apparently depends on the protein level of TET dioxygenases.The expression level of TETs is low in most terminally differentiated cells suchA n n u . 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F o r p e r s o n a l u s e o n l y .as fibroblasts but is relatively high in neuronal cells such as Purkinje cells (26,44).However,TETs are expressed at a much higher level in embryonic tissues,especially at early developmental stages (86).It is known that epigenetic reprogramming occurs during mammalian embryonic development,which involves DNA demethylation and remethylation.For a long time,it was unclear how the DNA is demethylated in preimplanted embryos.It is now known that both TET-mediated oxidation and passive dilution participate in the demethylation process.Immediately after fertilization,5mC in the paternal chromatin is rapidly replaced by 5hmC via TET3-mediated oxidation,which cannot be maintained during the rapid DNA replication in preimplanted embryos leading to passive demethylation and the erasing of paternal 5mC patterns (33).In contrast,the maternal DNA is only passively demethylated by dilution due to the inhibition of DNMT1;further TET-catalyzed oxidization of 5mC is not involved (42).However,one recent report showed that both the paternal and maternal chromatin went through active demethylation from zygote to four-cell embryos (89).A second round of epigenetic reprogramming that happens in primordial germ cells also involves TETs-mediated active demethylation (42).Currently available evidence suggests that TETs-mediated active demethylation is one of the major pathways for DNA demethylation during early embryonic development.As a result,it could be possible that varying levels of ascorbate during embryonic development affect epigenetic reprogramming of both germ cells and the developing embryo,which could lead to distinct conse-quences.To date,studies on the effects of ascorbate contents on DNA methylation-demethylation dynamics during embryonic development are still lacking.However,several studies suggest that deficiency of ascorbate is linked to certain types of developmental defects.For example,women at high risk for neural tube defect recurrence tend to have lower leukocyte ascorbate levels com-pared with low-risk women (3,77).Genetic variation in SVCT2,which might affect intracellular ascorbate levels,is also associated with the risk of preterm birth (16).However,due to the fact the ascorbate consumption from dietary sources and supplements is almost impossible to control quantitatively in human subjects,published results of ascorbate supplementation on birth defects or preterm delivery are mixed.It is worth noting that ascorbate supplementation in pregnant women should be aimed at satisfying the needs of TETs and other Fe 2+-and 2OG-dependent dioxygenases in both the mother and the embryo.In the case of sufficient ascorbate dietary in-take,higher doses of ascorbate may not necessarily exert additional benefits.Although ascorbate is probably essential for TETs-mediated active demethylation in embryonic development,it is unclear how much ascorbate is needed from the diet and/or supplements to completely satisfy the requirement of TETs for the prevention of embryonic defects caused by inappropriate DNA demethylation.Vitamin C and the Loss of 5hmC in CancerIn contrast to the relatively high level of 5hmC in embryos,especially in preimplanted embryos and primordial germ cells,cancer cells have very low or undetectable 5hmC.Studies have shown that loss of 5hmC is a novel epigenetic hallmark of most,if not all,types of human cancer (9,36,40,45,57,65,67,71,94,95).The Rao lab was the first to provide convincing evidence that links the mutant TET1and an impaired generation of 5hmC in leukemia (85).Since then,many groups have identified the loss of 5hmC in various cancers.In 2012,Shi and colleagues published findings of the inverse correlation of 5hmC with melanoma progression in humans and a possible treatment in animal models.The content of 5hmC is relatively high in healthy melanocytes but is gradually lost during progression from benign nevi through advancing stages of primary and metastatic melanoma (49).The global loss of 5hmC disrupts the normal dynamics of DNAA n n u . R e v . N u t r . 2015.35:545-564. D o w n l o a d e d f r o m w w w .a n n u a l r e v i e w s .o r g A c c e s s p r o v i d e d b y N o r t h w e s t A g r i c u l t u r e a n d F o r e s t r y U n i v e r s i t y o n 03/10/16. F o r p e r s o n a l u s e o n l y .。

素食主义英语作文The Rise of Vegetarianism: An Insight into Its Popularity and Benefits。

In recent years, vegetarianism has gained significant momentum, with an increasing number of individuals opting to exclude meat and animal-derived products from their diets. This shift in dietary preferences is not just a fad; it's a movement that's deeply rooted in concerns for animal welfare, environmental sustainability, and personal health.Firstly, vegetarianism finds its roots in compassionfor animals. The practice of raising animals for food production often involves cruel and inhumane methods that deprive them of their natural habitats and freedom. Many vegetarians believe that animals deserve to live freely and without suffering, and thus choose to abstain from consuming their flesh. This compassionate approach to diet is not just about food; it's a way of life that promotes kindness and empathy.Moreover, the environmental impact of meat production is another compelling reason for the rise of vegetarianism. The meat industry is a major contributor to greenhouse gas emissions, land degradation, and water pollution. By adopting a vegetarian diet, individuals can significantly reduce their carbon footprint and contribute to a more sustainable planet. This shift in dietary patterns can have a significant impact at a global level, as the collective efforts of millions of vegetarians can make a meaningful difference to the environment.In addition to its ethical and environmental benefits, vegetarianism also offers numerous health advantages. A plant-based diet is rich in fiber, vitamins, minerals, and antioxidants, which are essential for maintaining good。

金华“PEP”2024年小学三年级英语第6单元自测题考试时间：80分钟（总分:100）B卷考试人：_________题号一二三四五总分得分一、综合题(共计100题)1、听力题：The symbol for cadmium is _____.2、填空题：The ______ (植物的形状) can affect light absorption.3、听力题：The first successful test of an atomic bomb was in _______.4、What do we call the story of someone's life?A. BiographyB. NovelC. FictionD. Poetry5、听力题：My friend is a ______. He enjoys learning about space.6、听力填空题：School is a place where I learn many things. My favorite subject is __________ because I find it __________. I especially enjoy __________ during our lessons. My teacher,__________, always encourages us to __________. She believes that learning should be fun and exciting.7、填空题：I like to collect different kinds of ________ (玩具类型).8、What do we call the act of exploring new places?A. TravelingB. ExploringC. AdventuringD. All of the above答案: D. All of the above9、填空题：_____ (乡村生活) often revolves around plants and agriculture.10、听力题：His favorite movie is a ________.11、填空题：We built a _____ (沙堡) at the beach.12、What is the largest mammal in the world?a. Elephantb. Blue Whalec. Giraffed. Hippopotamus答案:b13、听力题：My sister is a ______. She loves to create art installations.14、填空题：We need to _______ (改善) our community.15、What is the hardest natural substance on Earth?A. GoldB. DiamondC. IronD. Quartz答案:B16、What do we call the time of year when leaves fall from trees?A. SpringB. SummerC. FallD. Winter答案: C. Fall17、Which continent is known for its deserts?A. AsiaB. AfricaC. EuropeD. Antarctica答案:BOxidation reactions involve the ________ of electrons.19、填空题：I love to ______ (尝试) new hobbies.20、填空题：Orchids are known for their beautiful ______ (花).21、听力题：The process of separating mixtures is called ______.22、What is the name of the famous bridge in San Francisco?A. Brooklyn BridgeB. Golden Gate BridgeC. London BridgeD. Sydney Harbour Bridge23、听力题：The _____ of an element is determined by the number of protons in its nucleus.24、听力题：A precipitate forms when two liquids ______.25、填空题：In _____ (巴西), Carnaval is a major celebration.26、听力题：Chemical changes often involve the formation or breaking of ________.27、填空题：The _____ (果实) of the apple tree is very sweet.28、填空题：A rabbit's diet is primarily made up of ________________ (草和蔬菜).29、听力题：Chlorine is used to disinfect _____ (water) in pools.30、听力题：The kids are _____ in the park. (running)31、听力题：The _____ (leaf) is green.The country famous for its lakes is ________ (加拿大).33、What do you call a baby zebra?A. ColtB. CalfC. KitD. Pup34、选择题：What is the name of the famous character known for his long hat and green jacket?A. The Cat in the HatB. The GrinchC. WaldoD. Peter Pan35、填空题：A stingray glides along the ________________ (海底).36、填空题：I like to play with my ________ (玩具名称) after school.37、填空题：The __________ is the capital city of Canada. (渥太华)38、填空题：The __________ (历史的再现) can evoke powerful emotions.39、听力题：The __________ Ocean is located between Europe and Asia.40、填空题：My grandmother tells me __________. (故事)41、填空题：He _______ (喜欢) playing soccer after school.42、听力题：My cousin is a ______. She enjoys solving problems.43、听力题：The dog is ________ in the park.44、What is the smallest continent?A. AsiaB. AfricaC. AntarcticaD. Australia答案:D45、听力题：The capital of Tuvalu is _______.46、听力题：A chemical that donates electrons is called a ______.47、What do you call the process of water turning into vapor?A. EvaporationB. CondensationC. PrecipitationD. Freezing答案:A48、听力题：A __________ is a geological feature that can shape human activities.49、听力题：The ______ helps with the coordination of movements.50、听力题：The chemical symbol for zinc is __________.51、What is the capital of the United Kingdom?A. LondonB. ParisC. RomeD. Berlin答案:A52、填空题：I enjoy ________ (晨跑) in the park.53、填空题：A ______ (植物资源管理) is vital for sustainability.54、What is the color of a typical chocolate bar?A. BrownB. WhiteC. BlackD. Purple答案:AI call my friend’s sister __________. (妹妹)56、听力题：The _______ of an object can be calculated using its volume.57、听力题：A sound wave can be represented by a ______ wave.58、听力题：My brother is a ______. He enjoys playing video games.59、填空题：The ________ is soft and warm.60、填空题：The museum is very _______ (有教育意义的).61、填空题：The _______ (小乌鸦) caws loudly in the tree.62、听力题：A ____ is often seen in gardens hopping around.63、听力题：The chemical formula for samarium(II) oxide is _____.64、填空题：A __________ day is good for hiking. (晴朗的)65、听力题：The _______ tells us the number of protons in an atom.66、填空题：The filmmaker produces amazing _____ (电影).67、填空题：The sun is shining ________ (明亮).68、What is the name of the famous painting by Leonardo da Vinci?A. The Last SupperB. Mona LisaC. The Starry NightD. The Scream答案:BThe _______ can be very colorful in the spring.70、填空题：The scientist, ______ (科学家), studies animals and plants.71、填空题：I saw a ________ jump over a fence.72、What is the name of the famous mountain in Asia?A. Mount EverestB. Mount KilimanjaroC. Mount FujiD. Mount McKinley答案:A73、填空题：The ancient Romans were known for their ________ and architecture.74、填空题：After the rain, the grass looks __________. (湿润的)75、What do you call a baby pig?A. CalfB. PigletC. LambD. Kid答案:B76、听力题：A polar molecule has regions of _______ charge.77、填空题：My pet rabbit has soft _______ (毛) that I like to pet.78、What is the name of the first female astronaut?A. Sally RideB. Mae JemisonC. Valentina TereshkovaD. Eileen Collins答案:C79、填空题：My puppy enjoys rolling in the ______ (草地).Which sport is played with a bat and ball?A. SoccerB. BasketballC. BaseballD. Swimming81、填空题：A wolverine is a strong ______ (动物).82、What is the name of the fairy tale character who loses her glass slipper?A. Snow WhiteB. CinderellaC. JasmineD. Belle答案: B83、填空题：The ________ was a significant trade route in Asia.84、填空题：The __________ (历史的探索) continues to reveal new truths.85、听力题：The __________ can reveal the history of tectonic plate movements.86、What do we call the study of animals in their natural habitat?A. EthologyB. EcologyC. ZoologyD. Botany答案: B87、听力题：The first person to summit Mount Everest was _______ Hillary.88、What is the main function of leaves on a plant?A. To growB. To photosynthesizeC. To bloomD. To shed答案:B89、听力题：The rabbit is ___ (eating) a carrot.My grandma knitted me a ________ (毛线玩具). It’s a cute little ________ (兔子).91、选择题：What do we call a person who studies astronomy?A. AstronomerB. AstrophysicistC. CosmologistD. All of the above92、填空题：My sister's favorite toy is a _____.93、What is the term for the distance around a circle?A. DiameterB. RadiusC. CircumferenceD. Area答案:C94、听力题：The girl is wearing a ________ dress.95、填空题：A __________ (无机化合物) does not primarily contain carbon.96、填空题：The frog jumps into the ______ (水). It makes a big ______ (水花).97、听力填空题：I enjoy going to the farmer's market to buy __________.98、What do we call the process of plants absorbing sunlight?A. RespirationB. PhotosynthesisC. TranspirationD. Combustion99、What do you call the main character in a comic book?A. HeroB. VillainC. SidekickD. Comic relief答案:AThe bear forages for food in the dense ____.。