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线粒体氧化磷酸化线粒体融合裂解线粒体是细胞内的能量工厂，通过氧化磷酸化来产生能量。
Mitochondria are the energy factories in the cells, producing energy through oxidative phosphorylation.线粒体融合可以增强线粒体的功能和稳定性。
Mitochondrial fusion can enhance the function andstability of mitochondria.线粒体裂解可以清除受损的线粒体，并维持细胞健康。
Mitochondrial fission can remove damaged mitochondria and maintain cell health.线粒体融合和裂解是细胞内动态平衡的重要组成部分。
Mitochondrial fusion and fission are important components of dynamic equilibrium within the cell.线粒体融合通过调节蛋白质的相互作用来促进。
Mitochondrial fusion promotes through regulating the interaction of proteins.线粒体裂解涉及到细胞骨架的参与。
Mitochondrial fission involves the participation of the cellular cytoskeleton.线粒体融合和裂解的失衡可能导致多种疾病的发生。
Imbalance of mitochondrial fusion and fission may lead to the occurrence of various diseases.线粒体融合抑制蛋白可以调节细胞内线粒体数量。
Mitochondrial fusion inhibitory proteins can regulate the number of mitochondria within the cell.线粒体裂解的调控受到细胞内环境的影响。
23年高考英语外刊阅读训练——阅读理解：人工智能如何转变教育——改编自How Artificial Intelligence Is Changing Education AI, or artificial intelligence, has bee increasingly prevalent in everyday life. Programmers code and "train〞puters to perform tasks that normally require human intelligence, such as visual recognition, artificial speech, and problem solving. AI algorithms work behind the scenes to customize ads and content online, and natural language processors interact and respond with users in a conversational manner. AI chatbots are now widely available and can be used for a variety of purposes such as customer service and generating sales leads.One example of an AI that may help protect individuals is “Take It Down,〞a bot developed by Meta to help teenagers remove unauthorized photos from the internet. While there are concerns about AI bots collecting data and invading privacy, AI automation can save time and improve efficiency in many areas, including this task that would otherwise take hours to perform manually.The current generation of AI chatbots still face limitations in fully simulating human emotions and attending to nuanced language cues in human conversations. This reflects the biases and stereotypes "learned" from their creators. AI developers must continue to work on improving AI processing and linguistics for a more humanized approach.AI may also change how we approach education and tutoring. AI tutoring programs and AIassisted mental health services could provide 24/7 accessibility for students and personalized assessments for academic, behavioral, and mental health issues. However, concerns remain over the potential misuse of AI technology for cheating and plagiarism in academic settings.Despite concerns about privacy and the scifi notion of AI robots taking over, AI will continue to open up new discoveries in all aspects of life. This technology carries both risks and benefits, but if used with care, it can bring positive developments while avoiding risks to livelihoods and privacy.【重点词汇】1. AI /ˌɑːtɪˌɪnˈtelɪdʒəns/ n. 人工智能，人工才智2. artificial /ˌɑːrtɪˈfɪʃl/ adj. 人造的，人工的3. intelligence /ɪnˈtelɪdʒəns/ n. 智能，才智4. programmer /ˈprəʊɡræmər/ n. 程序员，编程者5. code /kəʊd/ v. 编码，编程6. train /treɪn/ v. 训练，培育7. puter /kəmˈpjuːtə(r)/ n. 计算机，电脑8. visual /ˈvɪʒuəl/ adj. 视觉的，视力的9. recognition /rekəɡˈnɪʃn/ n. 认知，识别10. speech /spiːtʃ/ n. 语音，演讲11. problemsolving /ˈprɑːbləmˌsɑlvɪŋ/ n. 解决问题的力量12. algorithm /ˈælɡərɪðəm/ n. 算法，计算方法13. customize /ˈkʌstəmaɪz/ v. 定制，定做14. content /ˈkɒntent/ n. 内容，名目15. online /ˈɒnlaɪn/ adj. 在线的，联网的16. natural language /ˈnætʃrəl ˈleŋɡwɪdʒ/ 自然语言17. processor /ˈprəʊsesə(r)/ n. 处理器，处理机18. interact /ˌɪntərˈækt/ v. 相互作用，相互影响19. conversational /ˌkɑːnvəˈseɪʃənl/ adj. 对话的，会话的20. chatbot /ˈtʃætˌbɒt/ n. 谈天机器人21. available /əˈveɪləbl/ adj. 可获得的，可得到的22. customer service /ˈkʌstəməˈsɜːvɪs/ 客户效劳23. generate /ˈdʒenəreɪt/ v. 生成，产生24. sales lead /seɪlz liːd/ 销售线索25. protect /prəˈtekt/ v. 爱护，防护26. unauthorized /ˌʌnˈɔːθəraɪzd/ adj. 未经授权的，越权的27. image /ˈɪmɪdʒ/ n. 图像，形象28. privacy /ˈpraɪvəsi/ n. 隐私，保密29. automation /ˌɔːtəˈmeɪʃn/ n. 自动化，自动化掌握30. emotion /ɪˈməʊʃn/ n. 情感，心情31. nuanced /ˈnjuːɑːnst/ adj. 微小的，差异的32. cue /kjuː/ n. 示意，信号，提示33. bias /ˈbaɪəs/ n. 偏见，偏向34. stereotype /ˈsteriətaɪp/ n. 刻板印象，陈规旧习35. approach /əˈprəʊtʃ/ v. 接近，靠近36. education /ˌedʒuˈkeɪʃn/ n. 教育，教学37. tutor /ˈtjuːtə(r)/ n. 导师，辅导员，家庭老师38. mental health /ˌmentl ˈhelθ/ 心理健康39. accessible /əkˈsesəbl/ adj. 可得到的，可进入的40. selfpaced /self peɪst/ adj. 自我调整的，自学的【阅读理解练习题】1. What is the main purpose of "Take It Down"?A. To help teenagers remove unauthorized photos fromthe Internet.B. To collect data and invade privacy.C. To simulate human emotions in AI chatbots.D. To generate sales leads.答案：A中文解析：题目问的是“Take It Down〞的主要目的是什么，依据文章其次段第一句可知，“T ake It Down〞是Meta开发的一个机器人关心青少年从互联网上删除未经授权的照片。
MDH1介导苹果酸-天冬氨酸NADH穿梭维持胎儿肝造血干细胞的活性水平。
（Sonarsignal）MDH1-mediated malate-aspartate NADH shuttle maintains the activity levels of fetal liver hematopoietic stem cellsVisual Abstract造血干细胞在不同发育阶段的能量代谢和干细胞之间的关系仍然很大程度上是未知的。
我们为 NADH/NAD+ 传感器(SoNar)构建了一个转基因小鼠系，并根据 SoNar 荧光比率分析了3个不同的胎肝造血细胞群。
Sonar 值低的细胞线粒体呼吸水平增强，但糖酵解水平与sonar 值高的细胞相似。
有趣的是，10% 的 SoNar-low 细胞含有65% 的免疫表型胎儿肝造血干细胞(fl-hsc) ，并且比 SoNar-high 细胞含有大约五倍的功能性造血干细胞。
Sonar 能够敏感地监测体内外造血干细胞能量代谢的动态变化。
STAT3通过反式激活 MDH1维持苹果酸-天冬氨酸 NADH 的穿梭活性和 HSC 的自我更新和分化。
我们揭示了一个意想不到的fl-hsc 代谢程序，为造血干细胞或其他类型干细胞的代谢研究提供了一个强有力的遗传工具。
原文摘要：The connections between energy metabolism and stemness of hematopoietic stem cells (HSCs) at different developmental stages remain largely unknown.We generated a transgenic mouse line for the genetically encoded NADH/NAD+ sensor (SoNar) and demonstrate that there are 3 distinct fetal liver hematopoietic cell populations according to the ratios of SoNar fluorescence.SoNar-low cells had an enhanced level of mitochondrial respiration but a glycolytic level similar to that of SoNar-high cells. Interestingly, 10% of SoNar-low cells were enriched for 65% of total immunophenotypic fetal liver HSCs (FL-HSCs) and contained approximately fivefold more functional HSCs than their SoNar-high counterparts.SoNar was able to monitor sensitively the dynamic changes of energy metabolism in HSCs both in vitro and in vivo.Mechanistically, STAT3 transactivated MDH1 to sustain the malate-aspartate NADH shuttle activity and HSC self-renewal and differentiation.We reveal an unexpected metabolic program of FL-HSCs and provide a powerful genetic tool for metabolic studies of HSCs or other types of stem cells.Key Points•FL-HSCs mainly use oxidative phosphorylation but with normal glycolysis, as indicated by a highly responsive NADH/NAD+ sensor.•FL-HSC activities are tightly regulated by the STAT3/MDH1-mediated malate-aspartate NADH shuttle.Subjects:Hematopoiesis and Stem CellsTopics:aspartate, fetus, fluorescence, liver, malates, mice, transgenic, mitochondria, nicotinamide adenine dinucleotide (nad), stat3 protein, hematopoietic stem cellsIntroductionHematopoietic stem cells (HSCs) originate from the aorta-gonad-mesonephros region1 and migrate into the fetal liver (FL) and undergo dramatic expansion,2,3 gradually localizing to and residing in the bone marrow niche after birth.4HSCs can self-renew to maintain the stem cell pool and generate all downstream progenitors and terminally differentiate into multiple lineages.5,6Increasing evidence indicates that the metabolic state is tightly connected to HSC activity.7-9Adult HSCs preferentially undergo glycolysis, rather than oxidative phosphorylation, in the hypoxic niche,7,10,11 which is extensively regulated by several signaling pathways, including HIF1A,12 MYC,13 PDK,14 DLK-GTL2,15 and vitamin A–retinoic acid signaling.16We have also shown that both murine and human HSCs adopt a glycolytic metabolic profile under certain conditions andthat this profile is fine-tuned by MEIS1/PBX1/HOXA9/HIF1A signaling pathways.17-19Interestingly, recent studies have suggested that adult HSCs also have high mitochondrial mass and enhanced dye efflux but possess limited respiratory and turnover capacity,20 which indicates that mitochondria are likely required for the function of adult HSCs, as evidenced by the fact that FOXO3 serves as a regulator to couple mitochondrial metabolism with HSC homeostasis.21The metabolic profiles of FL-HSCs and the effects of metabolism on HSC function, however, remain largely unknown.FL-HSCs undergo rapid division/expansion, conceivably through an increased demand on energy sources compared with that needed by adult HSCs, which are usually maintained in a relatively quiescent state.It is also possible that distinct microenvironments in different hematopoietic organs may affect the metabolism of HSCs.Interestingly, a recent report showed that loss of Rieske iron-sulfur protein, a mitochondrial complex III subunit, impairs the quiescent status of adult HSCs and the differentiation capacity of FL-HSCs.22FL-HSCs seem to have increased expression levels of many mitochondrial respiration–related genes, although whether metabolic status determines the cell fate of FL-HSCs remains unknown.23Results from previous studies indicate that mitochondrial activity may play a role in HSCs in the FL stage, although the detailed metabolic profiles and their underlying mechanisms await further investigation.Because of limitations in the availability of HSCs, moststudies related to the nutrient metabolism of HSCs have depended heavily on flow cytometric analysis with MitoTracker dyes, TMRE, and DCFDA to determine mitochondrial mass, membrane potential, and ROS level, respectively.Improved techniques have been used to measure several metabolic features of HSCs, such as oxygen consumption and lactate generation9,24 ; however, these studies may not directly reflect the true extent of glycolysis, oxidative phosphorylation, or other metabolic processes in HSCs.Recent studies have provided interesting evidence showing that it is feasible to perform a metabolomic analysis with fewer than 104 HSCs to explore the metabolic networks of different types of nutrients.25Nevertheless, it remains difficult to detect all of the metabolites sensitively with a limited number of HSCs using conventional metabolomic analysis.Few tools are available for real-time imaging of metabolic states in live HSCs, either in vitro or in vivo. Therefore, alternative approaches, such as metabolite biosensors, are required for the direct, precise, and real-time detection of subtle changes in nutrient metabolism in HSCs.Recently, we developed a highly responsive NADH/NAD+ sensor, called SoNar,26 which was designed by inserting cpYFP into the NAD(H)-binding domain of T-Rex.SoNar shows distinct fluorescence responses to NADH and NAD+.Inside the cell under physiological conditions, the total intracellular pool of NAD+ and NADH in the range of hundreds of micromolars27-30 far exceeds the dissociation constants of SoNar for NAD+ (K d, 5.0 μM) and NADH (K d, 0.2 μM);thus, the sensor would be occupied by either NAD+ or NADH molecules, and its steady-state fluorescence would report the NAD+/NADH ratio rather than the absolute concentrations of either of the 2 nucleotides according to equilibrium thermodynamics.26In addition, SoNar fluorescence is intrinsically ratiometric （比率计）, with 2 excitation wavelengths, and its fluorescence excited at 420 (or 405) and 485 nm shows opposing responses to ligand binding.26,31This ratiometric property of a sensor is highly desired for quantitative imaging in live cells and in vivo,32,33 because it eliminates the differences in instrumental efficiency, environmental effects, and probe concentration, enabling it to be widely used in different biological samples.The SoNar sensor has a 15-fold (or 1500%) dynamic range, enabling us to measure the cytosolic NAD+/NADH ratio from 0.8 to 2000.26,31,34Interestingly, SoNar has many desirable properties that make it an ideal sensor; it has a rapid response, high sensitivity, intense fluorescence, and large dynamic range, and it is capable of reporting subtle perturbations in many pathways affecting energy metabolism, including glycolysis and mitochondrial respiration.We generated SoNar transgenic mice and examined the metabolic profiles of FL-HSCs and their contributions/connections to cell fate determinations, as well as the underlying mechanisms governing FL-HSC function.参考文献：/10.1182/blood.2019003940HEMATOPOIESIS AND STEM CELLS| JULY 30, 2020----------------------------------------------------------------------------------------------------------------------------MethodsMiceSoNar DNA consists of the sequence of cpYFP, truncated T-Rex (78-211), and the linkers between them.26 Its coding gene (1.2 kbp) is much smaller than those of the first-generation NADH sensors Peredox (2.8 kbp) and Frex35 (1.8 kbp). For transgenic studies, smaller is better for the expression of the sensor in cells and in vivo.31 To generate SoNar transgenic mice, SoNar DNA was cloned into the pCAG vector with chicken β-actinpromoter. The targeting construct was linearized, purified, and microinjected into FVB blastocysts. SoNar DNA was randomly incorporated into the genome and determined by polymerase chain reaction (PCR) assay. Messenger RNA (mRNA) and protein expressions of SoNar in different tissues of SoNar mice were further evaluated by both reverse transcription PCR (RT-PCR) and fluorescence microscopy. The resulting chimeric mice were bred with FVB mice to obtain germ line transmission. These mice were next backcrossed with a C57BL/6 CD45.2 background, and germ line transmission was checked by PCR and flow cytometry. Heterozygote transgenic SoNar mice were used for most of the experiments in the current study. C57BL/6 CD45.2 mice were purchased from the Shanghai SLAC Laboratory Animal Co., Ltd. CD45.1 mice were provided by Dr Jiang Zhu at Shanghai Jiao Tong University School of Medicine. All animal experiments were conducted according to the Guidelines for Animal Care at Shanghai Jiao Tong University School of Medicine. All these materials, including SoNar sensor, are available upon request.In vivo imaging of SoNar transgenic miceGenotyping, mRNA expression, and histology of SoNar transgenic miceCompetitive reconstitution assayMetabolic imaging and quantification of cytosolicNAD+/NADH ratio in living cellsReal-time metabolic imaging in the BM nicheFlow cytometryUltrahigh-performance LC–qTOF–MS analysisMicroarray and quantitative RT-PCRMetabolic analysisOxygen consumption rate (OCR) and extracellularacidification rate were determined in CD45.2+ SoNar-high and -low FL hematopoietic cells with the XF Cell Mito Stress Test Kit (Seahorse #103015-100) and XF Glycolysis Stress Test Kit (Seahorse #103020-100) according to the manufacturer’s instructions using a Seahorse XF96 analyzer. In brief, for the OCR analysis, 3 × 105 SoNar-high and -low FL hematopoietic cells were incubated in the 37°C carbon dioxide–free incubator in 175 μL of assay medium (XF Base Medium with 2 mM of glutamine, 1 mM of pyruvate, and 10 mM of glucose [pH, 7.4]; 37°C); 1.5 μM of oligomycin, 2 μM of FCCP, and 0.5 μM of rotenone/antimycin A were loaded in injection ports A, B, and C, respectively. For the detection of extracellular acidification rate, 3 × 105 CD45.2+ SoNar-high and -low FL hematopoietic cells were incubated in the 37°C carbon dioxide–free incuba tor in 175 μL of assay medium (XF Base Medium with 1 mM of glutamine [pH, 7.4]; 37°C); 10 mM of glucose, 1.5 μM of oligomycin, and 100 mM of 2-DG were loaded into injection ports A, B, and C, respectively. ATP level was analyzed using the ATP Bioluminescence Assay Kit HS II (Roche) according to the manufacturer’s protocol, and data were normalized to cell count. T o analyze the mitochondrial DNA (mtDNA) copy numbers, total genomic DNA was extracted from the indicated cells for comparing the copies of the mitochondrial-specific mt-ND4 gene with those of the nuclear B2m gene. The primer sequences used are shown in supplemental Table 1.For intracellular and extracellular pyruvate and lactate assays, the extracts were prepared from 5 × 106 CD45.2+ FL hematopoiet ic cells using 300 μL of ice-cold 0.5-M perchloric acid for each sample. Extracts were centrifuged at 10 000 g for 5 minutes at 4°C, and the supernatant was neutralized with 5 M ofKOH and centrifuged at 10 000 g for 5 minutes at 4°C. The supernatant was removed for assay. For the pyruvate assay, 180 μL of assay buffer (100 mM of potassium chloride [pH, 6.7], 1 mM of EDTA, 0.1% bovine serum albumin, 10 μM of flavin adenine dinucleotide, 0.2 mM of thiamine pyrophosphate, 0.5 U of pyruvate oxidase, 0.2 U of h orseradish peroxidase, and 50 μM of AmplexRed) was added to a 96-well plate containing 20 μL of the cell extract or medium containing extracellular pyruvate. Changes in fluorescence were measured every 30 seconds for 15 minutes at 37°C by a Synergy 2 Multi-Mode Microplate Reader with an excitation filter of 530 BP 40 nm and emission filter of 590 BP 35 nm at 37°C. Calibration experiments were performed with 20 μL of pyruvate standards (0, 10, 20, 40, 60, 100, and 200 μM per well). For the lactate assay, 180μL of assay buffer (PBS [pH, 7.4], 0.1% bovine serum albumin, 500 μM of NAD+, 0.5 U of lactate dehydrogenase (LDH), 0.2 U of diaphorase, and 10 μM of resazurin) was added to a 96-well plate containing 20 μL of the cell extract or medium containing extracellular lactate. Changes in fluorescence were measured every 30 seconds for 15 minutes at 37°C by a Synergy 2 Multi-Mode Microplate Reader with an excitation filter of 540 BP 25 nm and emission filter of 590 BP 35 nm at 37°C. Calibration experiments were performed with 20 μL of lactate standards (0, 10, 20, 40, 60, 100, and 200 μM per well). All samples were diluted to fit within the range of the standard curve and run in triplicate. For the evaluation of NADH/NAD+ ratios by a biochemical assay, 1 million SoNar-high and -low FL hematopoietic cells were sorted from E14.5 FLs and subjected to measurement of NADH/NAD+ level using a commercially available NADH/NAD+ assay kit (Sigma #MAK037) according to the manufacturer’s instructions.Immunoblot analysisSingle cell colony formingThe single CD45.2+ SoNar-high or -low FL hematopoietic cell was freshly isolated and plated onto a 35-mm poly-D-lysine hydrobromide-coated glass-bottom dish (Cellvis) and cultured in Stemspan serum-free medium (Stemcell Technologies) containing 10 ng/mL of murine SCF and 10 ng/mL of murine TPO (Peprotech) for 96 hours. The ratios of daughter cells derived from a single parent cell were recorded with excitation at 405 and 488 nm using Nikon A1 confocal microscopy and analyzed with Image J software.Luciferase reporter assaysThe luciferase reporter vector pGL4.27 containing the Mdh1 promoter was constructed to identify transcriptional activation of Mdh1 by STAT3. Indicated doses of pLVX-Stat3 (or negative control vector) plasmid along with pGL4.27-mdh1 promoter vector were cotransfected into 293T cells. Luciferase activities were measured according to the manufacturer’s instructions (Promega #E1910) by using a luciferase reporter system (GloMax Multi Instrument) 24 hours after transfection. ChIP assaysChromatin immunoprecipitation (ChIP) assays were performed using the ChIP Assay Kit (Beyotime #P2078). Briefly, 293T cells were overexpressed with pGL4.27-mdh1 promoter vector and STAT3 (with Strep II tag) crosslinked with 1% formaldehyde (S igma) at 37°C for 10 minutes, and precleared DNA was then used for immunoprecipitation with 4 mL of anti–Strep II antibody (Genescript) or rabbit control immunoglobulin G (CST) at 4°C overnight. For the sample input, 1% of the sonicated pre-cleared DNA was purified at the same time withthe precipitated immune complex. The ChIP samples were purified by the Gel and PCR Clean Up Kit (Necleospin). The STAT3-binding sequence was amplified by semiquantitative PCR using primers specific for the Mdh1 promoter region as listed in supplemental Table 1.Methylation-specific PCR assayGenomic DNA was extracted from 500 000 CD45.2+ SoNar-high and -low FL hematopoietic cells using a DNA extraction kit (Generay Biotech #GK0122). The promoter methylation status of MDH1 was determined by sodium bisulfate to convert unmethylated (but not methylated) cytosine to uracil, followed by analysis by methylation-specific PCR to amplify specifically either methylated or unmethylated DNA using the Zymoresearch kit (EZ DNA Methylation-Direct Kit D5020) according to the manufacturer’s instruction. The methylation-specific PCR primers are listed in supplemental Table 1.Statistical analysisStatistical analysis was performed using GraphPad and SPSS software (version 19.0). Data are represe nted as mean ± standard error of the mean. n represents the number of independent experiments or the number of cells or mice per group from independent experiments. All experiments were performed independently 3 to 5 times. Data were analyzed with a Student t test (2 tailed), 1-way analysis of variance with Tukey’s multiple comparison test, or 2-way analysis of variance with Sidak’s multiple comparison test according to the experimental design, and statistical significance was set at P < .05.Establishment of pan-tissue SoNar transgenic mice.Figure 2.SoNar indicates metabolically distinct populations of FL hematopoietic cells.Figure 3.SoNar-low FL hematopoietic cells exhibit similar glycolytic but enhanced mitochondrial activity compared with SoNar-high cells.Figure 4.Functional HSCs are enriched in SoNar-low FLhematopoietic cells.Figure 5.FL-HSCs respond differently to AOA stimulation in the BM niche compared with adult HSCs.Figure 6.MDH1 enhances the malate-aspartate NADH shuttle and decreases NADH/NAD+ level in SoNar-low FL-HSCs.Figure 7.STAT3 transactivates Mdh1 expression to maintain FL-HSC activities.。
可汗学院新SAT阅读真题下载到目前为止，新版SAT可汗学院官方不断放出更多真题，已经放出了68篇阅读，具体如下：Level 2 22篇，Level 3 21篇，Level 4 17篇，8篇Diagnostic Quiz，共68篇阅读！想要下载可汗学院68篇阅读真题的同学，请移步：/sat/news/603917.htmlLevel 2Science篇1Passage adapted from Nikhil Swaminathan, "Eat (Less) to Live (Longer)," ©2007 by Scientific American.Scientists have known for more than 70 years that the one surefire way to extend the lives of animals was to cut calories by an average of 30 to 40 percent. The question was: Why? Now a new study begins to unravel the mystery and the mechanism by which reducing food intake protects cells against aging and age-related diseases.Researchers report in the journal Cell that the phenomenon is likely linked to two enzymes—SIRT3 and SIRT4—in mitochondria (the cell's powerhouse that, among other tasks, converts nutrients to energy). They found that a cascade of reactions triggered by lower caloric intake raises the levels of these enzymes, leading to an increase in the strength and efficiency of the cellular batteries. By invigorating the mitochondria, SIRT3 and SIRT4 extend the life of cells, by preventing flagging mitochondria from developing tiny holes (or pores) in their membranes that allow proteins that trigger apoptosis, or cell death, to seep out into the rest of the cell."We didn't expect that the most important part of this pathway was in the mitochondria," says David Sinclair, an assistant professor of pathology at Harvard Medical School and a study co-author. "We think that we've possibly found regulators of aging."In 2003 Sinclair's lab published a paper in Nature that described the discovery of a gene that switched on in the yeast cell in response to calorie restriction, which Sinclair calls a "master regulator in aging." Since then, his team has been searching for an analogous gene that plays a similar role in the mammalian cell.The researchers determined from cultures of human embryonic kidney cells that lower caloric intake sends a signal that activates a gene inside cells that codes for the enzyme NAMPT (nicotinamide phosphoribosyltransferase). The two- to four-fold surge in NAMPT in turn triggers the production of a molecule called NAD (nicotinamide adenine dinucleotide), which plays a key role in cellular metabolism and signaling.The uptick in NAD levels activates the SIRT3 and SIRT4 genes, increasing levels of their corresponding SIRT3 and SIRT4 enzymes, which then flood the interior of the mitochondria. Sinclair says he's not sure exactly how SIRT3 and SIRT4 beef up the mitochondria's energy output, but that events leading to cell death are at the very least delayed when there are vast quantities of the enzymes.SIRT3 and SIRT4 are part of a family called sirtuins (SIRT1, which helps extend cell life by modulating the number of repair proteins fixing DNA damage both inside and outside the cell's nucleus, is also a member). SIRT is short for sir-2homologue—a well-studied protein that is known to extend yeast cell longevity. According to Sinclair, all of the mammalian SIRT genes (and their proteins) are possible drug targets for therapies aimed at extending life, as well as staving off age-related illnesses, such as Alzheimer's disease, cancers and metabolic disorders, like diabetes."I think SIRT3 is the next most interesting sirtuin from a drug development standpoint," Sinclair says. "It does protect cells, but there's growing evidence that it may mediate the benefits of exercise as well."Sinclair's lab is now working on developing what he calls a possible "supermouse" with elevated levels of NAMPT to see if it lives longer and is more disease-resistant than normal mice.Matt Kaeberlein, a pathologist at the University of Washington in Seattle, says that Sinclair's team has an interesting hypothesis connecting the mitochondria to longevity, but that it needs to be more directly tested in the context of dietary restriction. "If the NAMPT-overexpressing mice are long-lived and disease resistant, that will provide more support for this idea."Lifespan of Groups of Mice With Different Levels of Caloric ReductionAdapted from Weindruch R, et al. (1986). "The Retardation of Aging in Mice by Dietary Restriction: Longevity, Cancer, Immunity, and Lifetime Energy Intake." Journal of Nutrition, April, 116(4), 641-54.QUESTION 1 OF 11The author indicates that caloric reduction extends the life of a mammalian cell by11 The author indicates that caloric reduction extends the life of a mammalian cell byA) turning off those genes involved in apoptosis, or cell death.B) forcing the mitochondria to utilize different energy sources for fuel.C) reducing the production of NAD (nicotinamide adenine dinucleotide).D) initiating a series of steps that results in the increased production of certain enzymes.2 Based on the passage, SIRT-3 and SIRT-4 indirectly affect cell longevity byA) strengthening the mitochondrial membrane.B) fixing damage to the cell’s DNA.C) initiating cell death.D) diminishing the efficiency of the cell’s mitochondria.3 Which choice provides the best evidence for the answer to the previous question?A) lines 7-9 (“Researchers ... mitochondria”)B) lines 13-18 (“By ... cell.”)C) lines 38-41 (“The ... mitochondria”)D) lines 41-44 (“Sinclair ... enzymes”)94 The author’s use of the words “powerhouse” and “batteries” in the second paragraph serves mainly toA) emphasize that mitochondria are the most important components of the cell.B) suggest that mitochondria use an electrical gradient to produce energyC) stress that mitochondria are the main sources of energy for the cell.D) imply that mitochondria need to be recharged in order to function efficiently5 As used in line 15 (“flagging”), “flagging” most nearly meansA) breaking.B) shrinking.C) folding.D) weakening.6 The main purpose of the fifth paragraph (lines 30-37) is toA) suggest that caloric reduction has a different effect on yeast cells than mammalian cells.B) highlight the important role that the kidney plays in the aging process.C) clarify the intermediate steps between caloric reduction and improved mitochondrial efficiency.D) identify the negative relationship between NAMPT production and NAD production.7 The author implies that the results of Sinclair’s study will enable future scientists toA) reverse the aging process.B) diagnose patients with age-related illnesses from an earlier age.C) create mice that are essentially immortal.D) more effectively treat a number of age-related illnesses.8 Which choice provides the best evidence for the answer to the previous question?A) lines 45-50 (“SIRT ... longevity.”)B) lines 50-54 (“According ... diabetes.”)C) lines 59-62 (“Sinclair’s ... mice”)D) lines 67-69 (“If ... idea”)9 The main purpose of the graph is toA) illustrate the relationship between caloric intake and longevity in different groups of mice.B) highlight how caloric reduction affects SIRT-3 enzyme production in different groups of mice.C) suggest that caloric reduction affects mice differently than it affects yeast.D) indicate that it is likely impossible to produce a genetically enhanced “supermouse.”10 How does the information in the graph relate to the author’s claim that caloric reduction increases the longevity of mammalian cells?A) It supports the claim, but suggests that the differences in longevity are marginal after a 25% caloric reduction.B) It supports the claim since the average lifespan of each group of mice increases as caloric reduction increases.C) It does not support the claim since the group of mice that did not have any caloric reduction had the highest survival rate after 35 months.D) It does not support the claim since all four groups of mice had the same average lifespan.11 It can reasonably be inferred from the graph that, 30 months into the study,A) all of the mice in the “55% caloric reduction”group were still alive.B) all of the mice in the “25% caloric reduction”group were still alive.C) approximately 50% of the mice in the “no caloric reduction” group we re still alive.D) none of the mice in the “no caloric reduction” group were still alive.。
（全国卷）2025届高考英语2月高分模拟卷（卷7）（含解析）(时间：120分钟满分：120分)选择题部分第一部分阅读理解(共两节，满分50分)第一节(共15小题；每小题2.5分，满分37.5分)阅读下列短文，从每题所给的四个选项A、B、C和D中，选出最佳选项。
A（2024·河北衡水市·衡水中学高三月考）The Apollo Missions“That's one small step for a man. One giant leap for mankind.”—Neil Armstrong Apollo’s GoalsThe national effort that enabled Astronaut Neil Armstrong to speak those words as he stepped onto the lunar surface fulfilled a dream as old as humanity. Project Apollo’s goals went beyond landing Americans on the moon and returning them safely to Earth.Apollo 13Apollo 13 has been called a “successful failure,” because the crew never landed on the Moon, but they made it home safely after an explosion crippled their ship. When the associated heater was turned on during flight, the tankexploded depleting almost all of the power from the command module and forcing the crew to use the lunar module as a lifeboat. Jim Lovell, Fred Haise and Jack Swigert came home safely thanks to the mission control team’s improvised procedures and their own ability to implement them.(Launch: April 11, 1970; splashdown: April 17)Apollo 14Notable for the return of America’s first astronaut, Alan Shepard, to space, Apollo 14 also was probably the smoothest lunar landing to that point. The crew spent more than nine hours outside the lunar module and set up a number of experiments. Shepard set a new distance record by walking more than 9,000 feet on the lunar surface, pulling a hand cart to carry their tools and samples.(Launch: Jan. 31, 1971: lunar landing: Feb. 5: splashdown, Feb. 9) Apollo 15For the first time, humans drove a car on the Moon. The first of the Apollo “J” Missions-designed for longer stays on the Moon - the mission carried a lunar rover, which Commander David Scott and Lunar Module Pilot James Irwin used while they were on the surface for more than I8 hours. They traveled more than 17 miles in the rover, setting up experiments and collecting 170 pounds of samples. Before leaving the lunar surface, Scott conducted an experiment to test Galileo’s theory that objects in vacuum, without air resistance, would fall at the same rate. He dropped a geological hammer and a feather, which hit the ground at the same time, proving Galileo right.(Launch: July 26, 1971, lunar landing: July 30: splashdown: Aug. 7)1．Why has Apollo 13 been called a “successful failure”?A．Apollo 13 finally exploded as planned in space.B．All the crew succeeded in landing on the Moon.C．The crew managed to escape from a severe accident and returned to Earth. D．The crew finished the experiment although they failed to land on the Moon. 2．Which of the following is True according to the passage?A．It took five days for Apollo 14 to reach the Moon.B．The lunar rover was used as a lifeboat for space travel.C．Shepard tested Gali leo’s theory successfully on the Moon.D．Apollo 15 remained in space for the shortest period of time.3．Which of the following column is this article most likely to be found? A．Booming Science B．Exploring the Unknown C．Mechanical World D．Transforming MoonB（2024·黑龙江哈尔滨市第六中学校高三期末）Staying connectedWhen Central Bucks South became one of the first Philadelphia-area high schools to close because of the fear of novel coronavirus exposure in early March, 16-year-old sophomore Andrew Chen knew that things were not going to return to normal as quickly as some of his peers hoped.But still, the change from seeing his friends on the swim team during daily practices to learning alone at home was jarring.“I only have three years her e at South, and it pains me to see one of them being wasted,” Chen said.The coronavirus has changed everyone’s lives, but for students, the disruption feels particularly serious. Schools closed and graduation ceremonies were put off. Summer plans, such as camps, are up in the air.But right now, many students are trying to stay connected, struggling with false information, and finding out the best ways they can help –through online method.For Josh Harycki, 17, a senior student at the Shipley School in Philadelphia, the best way to help was to create a “social distancing promise” for young people.“I saw a lot of young people not paying attention,” he said. “They were … still going out, hanging out with others. I thought that there had to be a way to reach younger people, who were possibly not watching the news.”Harycki started a call to action on social media and then built a website with a map that followed and kept the locations of people who’d signed the promise. The site also shares links to accurate sources of information like the US Centers for Disease Control and Prevention.Harycki knows that his peers are worried they can’t connected with their friends in the same way, so he created the social distancing promise to strengthen that although everyon e might be physically distant, they’re still connected.“Part of what we’re showing is that you might feel like you’re the only one taking this seriously, but our map shows that you’re not alone,” he said. 4．What does the underlined word “jarring” in Parag raph 2 probably mean? A．naturalB．necessaryC．worryingD．reasonable5．Who does Harycki mainly want to reach?A．Friends who are worried and bored.B．Young people not aware of the situation.C．Younger students trying to help.D．People taking the coronavirus seriously.6．What’s Harycki’s purpose in creating the “social distancing promise”? A．To order young people to stay at home.B．To follow those infected with the coronavirus.C．To tell young folks of latest news about the coronavirus.D．To show young people that they are still connected.7．Why does the author describe Andrew Chen’s experience in the text?A．To explain what worried students most when schools closed.B．To show the different views of students toward the coronavirus.C．To show how the coronavirus affected students’ lives.D．To explain the proper reaction to the close of school.C（2024·全国高三专题练习） One night in 1966, Michael Chapman rushed into a folk-music club in Cornwall, England to get out of the rain, and soon found himself onstage playing the guitar.“They offered me a job to play for the rest of the summer. And I’ve been playing ever since,” Chapman says. “I’ve told that story so many times, but it’s absolutely true. If it hadn’t been raining that night, I wouldn’t be talking to you.”The British guitar player has spent the 50 years since then on the road. He released some praised albums in the 1970s, but his health went downhill in the 80s and 90s. Like a lot of British artists in the 1960s, Chapman taught himself to play the guitar by listening to American jazz and blues records.Chapman actually taught photography, but quit when he was 26 to play music full time. When he was starting out, he was often compared to other British acoustic guitar heroes of the time, like John Martyn and Bert Jansch.“The fascinating thing about Michael Chapman is that he doesn’t fit in with those guys of his generation,” says Andrew Male, a music journalist. “He’s always been an outsider. He never moved to London. ”And while he never became part of the London music scene, Chapman was noticed by those musicians. “The 70s caught up with him in the 80s,” Male says. “He had a huge heart attack at the end of the 80s that nearly finished him off. When he made his way back into the world in the early 90s, people had forgotten about him.” But not everyone. A younger generation of musicians in America, including Thurston Moore of Sonic Youth and a younger singer and guitarist named Steve Gunn, recently rediscovered Chapman.“We wanted to capture Michael’s voice and character where he is now. You know, it’s a little road-weary, but he still has it,” Gunn says. “For me, it was really important to get that right.” “He’s the right old musician for present times,” Male says. “I think the music he makes seems quite in tune with where we’re at.”8．Which can best describe Michael Chapman’s first involvement in music? A．Untrue. B．Accidental. C．Unfortunate. D．Reasonable. 9．What can we learn about Michael Chapman from the text?A．He has taught photography for 26 years.B．He taught himself to play the guitar and did far better than John Martyn. C．To some degree, he is not accepted by other people of his generation. D．He is one of the best guitar players in the early 90s.10．Why did Michael Chapman quit his music career once?A．He lost his special voice. B．He suffered from a severe heart attack.C．He got tired of competing with others. D．He was almost forgotten by everyone.11．Which of the following can be the best title for the text?A．The Rise and Fall of Guitar Music B．The Sad Story of a Guitar Musician C．A New Generation Helps an Old Guitar Musician D．A Brief Introduction to a Guitar MusicianD（2024·天水市第一中学高三月考） How many times a day do you check your email? When you wake up? Before bed? A dozen limes in between? The technology that was supposed to make our lives simple has taken up too much time. The average teen spends more than seven hours a day using technological devices, with an additional hour just text-messaging friends.The advantage of technological devices is connectedness. Email lets us respond on the go, and we are in touch with more people during more hours of the day than at any other time in history. But is it possible that we’re lonelier than ever, too? That’s what MIT professor Sherry Turkle observes in her new book, Alone Together, which clearly describes our changing relationship with technology.For Turkic, the biggest worry is the effect the weak connections have on our development. T echnology isn’t offering us the lives we want to live. “We’re texting people at a distance” says Turkic. “We’re using lifelessobjects to convince ourselves that even when we’re alone, we feel together. And then when we’re with each other, we put ourselves in situations where we are alone—always on our mobile devices. It’s what I call a perfect storm of confusion about what’s important in our human connections.”Moreover, communicating online is not equal to face-to-face communication. Online, you can ignor e others’ feelings. In a text message, you can avoid eye contact A number of studies have found that this generation of young people is sympathetic (有怜悯心的) than ever. “That doesn’t lead to disaster,” says Turkle, “but the disadvantages still cannot be ignored.”12．From the first paragraph we can learn that .A．Email checking helps people wake up earlyB．People communicate mainly by text-messaging nowC．Technological device production has been simplifiedD．Using technological devices costs young men much time13．What is Sherry Turkic’s biggest worry?A．Technology may make human connections confusing.B．Technology can’t help people remove loneliness.C．Technology may make people’s lives hard.D．Technology keeps people together.14．What is the author’s at titude towards the influence of technology on people’s life?A．Positive B．NegativeC．Hopeless D．Uncertain15．What is the passage mainly about?A．Technology brings many conveniences to people’s lives.B．Young men spend too much time on technological devices.C．Technology also brings people some disadvantages.D．Sherry Turkle observes people’s changing relationship with Technology.其次节(共5小题；每小题2.5分，满分12.5分)依据短文内容，从短文后的选项中选出能填入空白处的最佳选项。
2020年9月英语六级真题及参考答案【完整版】四六级试卷采用多题多卷形式，大家核对答案时，请找具体选项内容，忽略套数。
无忧考网搜集整理了各个版本(有文字也有图片)，仅供大家参考。
【网络综合版】听力：Section ALong Conversation OneM: You are a professor of Physics at the University of Oxford. You are a senior advisor at the European Organization for Nuclear Research. You also seem to tour the global tirelessly, giving talks. And in addition, you have your own weekly TV show On Science. Where do you get the energy?W: Oh, well. 【Q1】I just love what I do. I am extremely fortunate to have this life, doing what I love doing.M: Professor, what exactly is your goal? Why do you do all of these?W: well, as you said, I do have different things going on. But these I think can be divided into 【Q2】two groups: the education of science, and the further understanding of science.M: Don't these two things get in the way of each other? What I mean is, doesn't giving lectures take time away from the lab?W: Not really, no. I love teaching, and I don’t mind spending more time doing that now than in the past. Also, what I will say is, that 【Q3】teaching a subject helps me comprehend it better myself. I find that it furthers my own knowledge when I have to explain something clearly, when I have to aid others understanding it, and when I have to answer questions about it. Teaching at a high level can be very stimulating for anyone, no matter how much expertise they may already have in the field they are instructing.M: Are there any scientific breakthroughs that you see on the near horizon? A significant discovery or invention we can expect soon.W: 【Q4】The world is always conducting science. And there're constantly new things being discovered. In fact, right now, we have too much data sitting in computers.For example, we have thousands of photos of planet Mars taken by telescopes that nobody has ever seen. We have them, yet nobody has had time to look at them with their own eyes, let alone analyze them.Q1: Why does the woman say she can be so energetic?Q2: What has the woman been engaged in?Q3: What does the woman say about the benefit teaching brings to her?Q4: How does the woman say new scientific breakthroughs can be made possible?Section AConversation 2M: Do you think dreams 【Q5】have special meanings?W: No. I don't think they do.M: I don't either, but some people do. I would say people who believe that dreams have special meanings are superstitious, especially nowadays. In the past, during the times of ancient Egypt, Greece or China, people used to believe that dreams could foresee the future. But today, with all the scientific knowledge that we have, I think it's much harder to believe in these sorts of things.W: My grandmother is superstitious, and she thinks dreams can predict the future. Once, 【Q6】she dreamed that the flight she was due to take the following day crashed.Can you guess what she did? She didn't take that flight. She didn't even bother to go to the airport the following day. Instead, she took the same flight but a week later. And everything was fine of course. No plane ever crashed.M: How funny! Did you know that flying is actually safer than any other mode of transport? It's been statistically proven. People can be so irrational sometimes.W: Yes, absolutely. But, even if we think they are ridiculous, 【Q7】emotions can be just as powerful as rational thinking.M: Exactly. People do all sorts of crazy things because of their irrational feelings. But in fact, some psychologists believe that our dreams are the result of our emotions and memories from that day. I think it was Sigmund Freud who said that children's dreams were usually simple representations of their wishes, thingsthey wished would happen. 【Q8】But in adults', dreams are much more complicated reflections of their more sophisticated sentiments.W: Isn't it interesting how psychologists try to understand using the scientific method something as bazaar as dreams? Psychology is like the rational study of irrational feelings.Q5: What do both speakers think of dreams?Q6: Why didn't the woman's grandmother take her scheduled flight?Q7: What does the woman say about people's emotions?Q8: What did psychologist Sigmund Freud say about adults' dreams?Section BPassage 1While some scientists explore the surface of the Antarctic, others are learning more about a giant body of water -- four kilometers beneath the ice pack. Scientists first discovered Lake Vostok in the 1970s by using radio waves that penetrate the ice. Since then, they have used sound waves and even satellites to map this massive body of water. How does the water in Lake Vostok remained liquid beneath an ice sheet? “The thick glacier above acts like insulating blanket and keeps the water from freezing,” said Martin Siegert, a glaciologist from the university of Wales. In addition, geothermal heat from the deep within the earth may warm the hidden lake.The scientists suspect that microorganisms may be living in Lake Vostok, closed or more than two million years. Anything found that off from the outside world f s on the surface of the earth, said Siegert. Scientists ’will be totally alien to what are trying to find a way to drill into the ice and draw water samples without causing ht be the solution. If all goes as planned, a contamination. Again, robots mig shift robot will melt through the surface ice. When it reaches the lake, it -drill will release another robot that can swim in the lake, take pictures and look for ries will shed light on life in outer signs of life. The scientists hope that discove up -space, which might exist in similar dark and airless conditions. Recently closed s moon, Europa, shows signs of water beneath the icy surface. ’pictures of Jupiter ropa to search for life there, Once tested the Antarctic, robots could be set to Eu too.Q9: What did the scientists first use to discover Lake Vostok in the 1970s? Q10: What did scientists think about Lake Vostok?Q11: What do the scientists hope their discoveries will do?Section BPassage 2The idea to study the American Indian tribe – Tarahumaras, came to James Copeland in 1984 when 【Q12】he discovered that very little research had been done on their language. He contacted the tribe member through a social worker who workedwith the tribes in Mexico. At first, the tribe member named Gonzalez was very reluctant to cooperate. He told Copeland that no amount of money could buy his language. But after Copeland explained to him what he intended to do with his research and how it would benefit the Tarahumaras, Gonzalez agreed to help. 【Q13】He took Copeland to his village and served as an intermediary. Copeland says, thanks to him, the Tarahumaras understood what their mission was and started trusting us. 【Q14】Entering the world of Tarahumaras has been a laborious project for Copeland.To reach their homeland, he must strive two and half days from Huston Taxes. He loads up his vehicle with goods that the tribe’s men can’t easily get and gives the goods to them as a gesture of friendship. The Tarahumaras, who don’t believe any humiliating wealth, take the food and share among themselves. For Copeland, the experience has not only been academically satisfying but also has enriched his life in several ways. 【Q15】“I see people rejecting technology and living a very hard, traditional life, which offers me another notion about the meaning of progress in the western tradition,” he says, “I experienced the simplicity of living in nature that I would otherwise only be able to read about.I see a lot of beauty and their sense of sharing and concern for each other.”Q12: Why did James Copeland want to study the American Indian tribe -- Tarahumaras?Q13: How did Gonzalez help James Copeland?Q14: What does the speaker say about James Copeland’s trip to the Tarahumaras village?Q15: What impresses James Copeland about the Tarahumaras tribe?Section CRecording 1What is a radical? It seems today that people are terrified of the term,minority, who are mostly wealthy white males in western society.Feminism is a perfect example of this phenomenon. The women's movement has been plagued by stereotypes, misrepresentations by the media, and accusations of man-hating and radicalism. When the basic foundation of feminism is simply that women deserve equal rights in all facets of life. When faced with the threat of being labelled radical, women back down from their worthy calls and consequently, participate in their own oppression.It has gotten to the point that many women are afraid to call themselves feminists because of a stigma attached to the word. If people refused to be controlled, and intimidated by stigmas, the stigmas lose all their power, without fear on which they feed, such stigmas can only die.To me, 【Q17】a radical is simply someone who rebels against the norm when advocates a change in the existing state of affairs. On close inspection, it becomes clear that the norm is constantly involving, and therefore, is not a constant entity. So why then, is deviation from the present situation such a threat, when the state of affairs itself is unstable and subject to relentless transformation?It all goes back to maintaining the power of those who have it and preventing the right of those who don't. In fact, when we look at the word "radical" in a historical context, nearly every figure we now hold up as a hero was considered a radical in his or her time. Radicals are people who affect change. They are the people about whom history is written. Abolitionists were radicals, civil rights activists were radicals, 【Q18】 even the founders of our country in their fight to win independence from England were radicals. Their presence in history has changed the way our society functions, mainly by shifting the balance of power that previously existed. Of course, there are some radicals who've made a negative impact on humanity, 【Q18】 but undeniably, there would simply be no progress without radicals. That been said, next time someone calls me a radical, I would accept that label with pride.Q16: What usually happens when people are accused of being radical?Q17: What is the speaker's definition of a radical?Q18: What does the speaker think of most radicals in the American history?Recording 2We are very susceptible to the influence of the people around us. For instance, you may have known somebody who has gone overseas for a year or so and has returned with an accent perhaps. We become part of our immediate environment. None of us are immune to the influences of our own world and let us not kid ourselves that we are untouched by the things and people in our life.Fred goes off to his new job at a factory. Fred takes his ten-minute coffee break, but the other workers take half an hour. Fred says, “What’s the matter with you guys?” Two weeks later, Fred is taking twenty-minute breaks. A month later, Fred takes his half hour. Fred is saying “If you can’t be them, join them. Why should I work any harder than the next guy?” The fascinating thing about being human is that generally we are unaware that there are changes taking place in our mentality. It is like returning to the city smog after some weeks in the fresh air. Only then do we realize that we’ve become accustomed to the nasty smells. Mix with critical people and we learn to criticize. Mix with happy people, and we learn about happiness. What this means is that we need to decide what we want from life and then choose our company accordingly. You may well say, "That is going to take some effort. It may not be comfortable. I may offend some of my present company." Right, but it is your life. Fred may say, "I’m always broke, frequently depressed. I’m going nowhereand I never do anything exciting." Then we discover that Fred’s best friends are always broke, frequently depressed, going nowhere and wishing that life was more exciting. This is not coincidence, nor is it our business to stand in judgement of Fred? However, if Fred ever wants to improve his quality of life, the first thing he'll need to do is recognize what has been going on all these years.It’s no surprise that doctors as a profession suffer a lot of ill health, because they spend their life around sick people. Psychiatrists have a higher incidence of suicide in their profession for related reasons. Traditionally, nine out of ten children whose parents smoke, smoke themselves. Obesity is in part an environmental problem. Successful people have successful friends, and so the story goes on.Q19 What does the speaker say about us as human beings?Q20 What does the speaker say Fred should do first to improve his quality of life?Q21 What does the speaker say about the psychiatrists?Section CLecture 3Virtually every American can recognize a dollar bill at a mere glance. Many can identify it by its sound or texture. But 【Q22】few people indeed can accurately describe the world's most powerful, important currency.The American dollar bill is colored with black ink on one side and green on the other;【Q23】 the exact composition of the paper and ink is a closely guarded government secret. Despite its weighty importance, the dollar bill actually weighs little. It requires nearly 500 bills to tip the scales at a pound. Not only is the dollar bill lightweight, but it also has a brief life span. Few dollar bills survive longer than 18 months.The word "dollar" is taken from the German word "taler," the name for the world's most important currency in the 16th century. The taler was a silver coin first minted in 1518 under the reign of Charles V, Emperor of Germany.The concept of paper money is a relatively recent innovation in the history of American currency. When the Constitution was signed, people had little regard for paper money because of its steadily decreasing value during the colonial era.【Q24】Because of this lack of faith, the new American government minted only coins for common currency. Interest-bearing bank notes were issued at the same time, but their purpose was limited to providing money for urgent government crises, such as American involvement in the War of 1812.The first noninterest-bearing paper currency was authorized by Congress in 1862, at the height of the Civil War. At this point, citizens' old fears of devalued paper currency had calmed, and the dollar bill was born. The new green colored paper money quickly earned the nickname "greenback."Today, the American dollar bill is a product of the Federal Reserve and is issued from the twelve Federal Reserve banks around the United States. The government keeps a steady supply of approximately two billion bills in circulation at all times.Controversy continues to surround the true value of the dollar bill.【Q25】American history has seen generations of politicians argue in favor of a gold standard for American currency. However, for the present, the American dollar bill holds the value that is printed on it, and little more. The only other guarantee on the bill is a Federal Reserve pledge of as a confirmation in the form of government securities.Q22: What does the speaker say about the American dollar bill?Q23: What does the speaker say about the exact composition of the American dollar bill?Q24: Why did the new American government mint only coins for common currency?Q25: What have generations of American politicians argued for?参考答案1.A)She can devote all her life to pursing her passion.2.D)Science education and scientific research.3.A)A better understanding of a subject.4.B)By making full use of the existing data.5. B) They have no special meanings.6. C) She dreamed of a plane crash.7. D) They can have an impact as great as rational thinking8. C) They reflect their complicated emotions.9. A) Radio waves.10. B)It may have micro—organisms living in it.11. D)Shed light on possible life in outer space.12. A)He found there had been little research on their anguage.13. D)He acted as an intermediary between Copel and the villagers.14. C)Laborious15. B)Their sense of sharing and caring.16 .A)They tend to be silenced into submission.17. D)One who rebels against the existing social orser.18. C)They served as a driving force for progress.19. B)It is impossible for us to be immune from outside influence.20. D) Recognize the negative impact of his coworkers.21. A) They are quite susceptible to suicide.22. B) Few people can describe it precisely.23. C) It is a well—protected government secret.24. A) People had little faith in paper money.25. C) It is awell—protected government secret.翻译：《水浒传》(Water Margin)是中国文学四大经典小说之一。
胎盘,线粒体动力学Apoptosis, or programmed cell death, is a fundamental process in the development and maintenance of multicellular organisms. It plays a critical role in variousphysiological processes, including embryonic development, tissue homeostasis, and the immune response. The regulation of apoptosis is a complex and tightly controlled process involving a variety of molecular and cellular mechanisms.Mitochondria, the powerhouse of the cell, are central players in the regulation of apoptosis. They are responsible for the generation of ATP, the energy currency of the cell, through a process called oxidative phosphorylation. In addition to their role in energy production, mitochondria also play a crucial role in the initiation and execution of apoptosis.Mitochondrial dynamics, including fission, fusion, and movement, are tightly regulated and play a critical role in the maintenance of mitochondrial function and integrity.Disruption of mitochondrial dynamics has been implicated in various human diseases, including neurodegenerative disorders, metabolic diseases, and cancer.Mitochondrial fission, the process by which a single mitochondrion divides into two daughter mitochondria, is regulated by a protein complex known as the dynamin-related protein 1 (Drp1). Drp1 is recruited to the outer mitochondrial membrane, where it assembles into a ring-like structure and constricts the membrane, leading to mitochondrial division. The balance between mitochondrial fission and fusion is crucial for maintaining mitochondrial function and cellular homeostasis.In addition to their role in mitochondrial dynamics, mitochondria also play a central role in the regulation of apoptosis. The release of pro-apoptotic factors from the mitochondrial intermembrane space, such as cytochrome c, triggers the activation of caspases, a family of protease enzymes that orchestrate the dismantling of the cell during apoptosis. This process is tightly regulated and can be influenced by various factors, including cellular stress,DNA damage, and the activation of specific signaling pathways.The placenta, an organ that develops during pregnancy to provide oxygen and nutrients to the developing fetus, also plays a critical role in the regulation of apoptosis. The placenta undergoes extensive remodeling and growth during pregnancy, and the balance between cellproliferation and apoptosis is crucial for its proper development and function. Dysregulation of apoptosis in the placenta has been implicated in various pregnancy-related complications, including preeclampsia and intrauterine growth restriction.Overall, the regulation of apoptosis and mitochondrial dynamics is a complex and tightly controlled process that plays a critical role in various physiological and pathological conditions. Understanding the molecular mechanisms underlying these processes is essential for the development of novel therapeutic strategies for the treatment of human diseases.英文回答，Mitochondrial dynamics, including fission, fusion, and movement, are tightly regulated and play a critical role in the maintenance of mitochondrial function and integrity. Disruption of mitochondrial dynamics hasbeen implicated in various human diseases, including neurodegenerative disorders, metabolic diseases, and cancer.Mitochondrial fission, the process by which a single mitochondrion divides into two daughter mitochondria, is regulated by a protein complex known as the dynamin-related protein 1 (Drp1). Drp1 is recruited to the outer mitochondrial membrane, where it assembles into a ring-like structure and constricts the membrane, leading to mitochondrial division. The balance between mitochondrial fission and fusion is crucial for maintaining mitochondrial function and cellular homeostasis.In addition to their role in mitochondrial dynamics, mitochondria also play a central role in the regulation of apoptosis. The release of pro-apoptotic factors from the mitochondrial intermembrane space, such as cytochrome c, triggers the activation of caspases, a family of proteaseenzymes that orchestrate the dismantling of the cell during apoptosis. This process is tightly regulated and can be influenced by various factors, including cellular stress, DNA damage, and the activation of specific signaling pathways.The placenta, an organ that develops during pregnancy to provide oxygen and nutrients to the developing fetus, also plays a critical role in the regulation of apoptosis. The placenta undergoes extensive remodeling and growth during pregnancy, and the balance between cellproliferation and apoptosis is crucial for its proper development and function. Dysregulation of apoptosis in the placenta has been implicated in various pregnancy-related complications, including preeclampsia and intrauterine growth restriction.Overall, the regulation of apoptosis and mitochondrial dynamics is a complex and tightly controlled process that plays a critical role in various physiological and pathological conditions. Understanding the molecular mechanisms underlying these processes is essential for thedevelopment of novel therapeutic strategies for the treatment of human diseases.中文回答，线粒体动力学，包括分裂、融合和运动，受到严格调控，在维持线粒体功能和完整性方面起着关键作用。
