A Unique Oscillation Solution to the Solar Neutrino Problem

小学上册英语第四单元综合卷[有答案]英语试题一、综合题(本题有50小题，每小题1分，共100分.每小题不选、错误，均不给分)1 Which shape has four equal sides?A. RectangleB. TriangleC. SquareD. Circle2 My brother loves to __________ (参加) science fairs.3 Bees help __________ (授粉) the flowers.4 What do we wear on our heads?A. ShoesB. GlovesC. HatD. Scarf答案: C5 The __________ is the area where fresh water meets salt water.6 She is good at ______. (dancing)7 The car is parked _____ (in front/behind) the house.8 Which season is cold?A. SummerB. FallC. WinterD. Spring9 What is the capital of Malaysia?A. Kuala LumpurB. GeorgetownC. MalaccaD. Johor Bahru答案:A10 What is the main ingredient in pizza dough?a. Cheeseb. Saucec. Flourd. Pepperoni答案:c11 The chemical formula for lawrencium oxide is ______.12 A cactus is a type of ________ (植物).13 ts are ______ (观赏性) and beautiful. Some pla14 What do you call the part of the plant that absorbs sunlight?A. RootB. LeafC. StemD. Flower15 I can ________ my friends.16 What is the name of the famous mountain in the United States?A. Mount EverestB. Mount RushmoreC. Mount KilimanjaroD. Mount Fuji17 What is the name of the person who fixes electrical problems?A. PlumberB. ElectricianC. CarpenterD. Mechanic18 Carta influenced the development of modern ________. The Magn19 The monkey is a playful _______ that swings from trees.20 The first successful kidney transplant was performed in ________.21 What do you call the study of living organisms?A. PhysicsB. ChemistryC. BiologyD. Astronomy答案:C22 What do we call a group of dolphins?A. SchoolB. PodC. FlockD. Colony答案:B. Pod23 They are eating ________ for lunch.24 Which animal is known for its stripes?A. LionB. ElephantC. ZebraD. Giraffe25 I have a _____ (滑梯) in my backyard. I love to slide down it! 我在后院有一个滑梯。

核磁自旋回波串的液体分量分解快速反演法孙伯勤;邓克俊【摘要】该文叙述核磁自旋回波串的液体分量分解快速反演法.此方法假定液体, 无论是在散装形式或饱和多孔介质中, 可以用一个或一组核磁弛豫线形来表征.对一维核磁共振的拉普拉斯反演, 它可以是预先确定的一个或一组T2或T1分布.对二维核磁共振的拉普拉斯反演, 它可以是一个或一组预先确定的(D,T2)或(T1,T2)二维分布.对三维核磁共振的拉普拉斯反演, 它可以是一个或一组预先设定的(D,T1,T2)三维分布.这些预先确定的线形, 可以是高斯、 B样条或预先由实验或经验确定的任何线形.这种方法可以显着降低核磁共振数据反演的计算时间, 特别是从石油核磁共振测井采集的多维数据反演, 它不需牺牲反演所得的分布的平滑性和准确性.这种方法的另一个新应用是作为一种约束求解方法来过滤相邻深度所采集的数据噪音.核磁共振测井的噪音信号, 往往造成在相邻深度的同一岩性岩层有不同的T2分布.在此情况下, T2分布就不能用来识别岩性.通过非一般的矩阵操作, 作者成功实现了对相邻深度的回波串实施约束求解方法, 从而使得T2分布成为一种可靠的岩性识别指标.【期刊名称】《波谱学杂志》【年(卷),期】2010(027)003【总页数】12页(P298-309)【关键词】核磁共振测井;弛豫分布;拉普拉斯反演;液体分类【作者】孙伯勤;邓克俊【作者单位】圣拉蒙市博林杰峡谷6001号,雪佛龙能源技术公司,加利福尼亚州,94583,美国;圣拉蒙市博林杰峡谷6001号,雪佛龙能源技术公司,加利福尼亚州,94583,美国【正文语种】中文【中图分类】O482.53IntroductionIt is well known that inverting the CPMG[1,2] T2 echo trains from an NMR logging measurement to obtain the T2 distributions is an ill-posed problem. The problem can be written as follows:(1)where bi is the measured signal of the i-th echo in a train of n echoes with a noise of ei at a decay time ti, and fj is the amplitude to be solved of the j-th T2 relaxation time for a set of m preselected T2’s equally spaced on a logarithmic scale. Eq. (1) is just an example of a Fredholm equation of the first kind:(2)in discrete form, where, K(t,T)=e-t/T, is the kernel. When the data b(t) cannot be measured free of noise, the uniqueness of the solution f(T) cannot be guaranteed. Small measurement error in b(t) could lead to great instability in the solution f(T). Various inversion schemes and regularizationprocesses were discussed[3] and proposed for suppressing such instability and obtaining a physical plausible solution. One of the ways to suppress the oscillation in the solution is to add a penalty term which is proportional to the norm, or the first or second derivative of f(T). It is also customary to use a large number of preselected T2 relaxation times to ensure a proper reflection of the true T2 distribution. Such practice does not pose any particular problem for this 1D NMR inverse Laplace transform problem as far as the computation time is concerned, where only the T2 distribution is inverted from a CPMG echo train. However, the computation time can become extremely long when one is handling 2D or even 3D NMR inverse Laplace transform problem[4] when large numbers of T2 relaxation times and diffusion coefficients, D, are used. There is an inversion method, called the basis function approach, which does not offer any particular benefit over the commonly used singular value decomposition (SVD) or Butler-Reeds-Dawson (BRD) method[3,5] for the 1D problem, is quite attractive for the 2D and 3D problems due to its efficient inversion speed. We shall now elaborate it as the “Fluid Component Decomposition” (FCD) method in the following.1 Fluid Component Decomposition MethodThe basis function approach, first suggested by Liaw et al.[6] using B-splines, can be described as follows:(3)where the solution is replaced by a set of basis functions:(4)and the number of the basis functions, Ns, can be much smaller than m, the number of the assumed T2 relaxation times equally spaced on a logarithmic scale. Thus, Eq.(1) can be rewritten as:(5)where Bjs is the discretized form of Bs(T) over the logarithmic relaxation time axis and Cs’s instead of fj’s are the u nknowns we want to solve. Now with a matrix of inversion of much smaller dimension, the inversion speed is much faster.Liaw et al. used B-splines as the basis functions. In fact, one can use Gaussian, gamma[7], or any other similar type of function as the basis function. If the basis function is broad enough, the regularizing action is already included, and no penalty term is needed.There are several ways to implement this FCD method. One is to have these basis functions also equally spaced on the logarithmic relaxation time axis[8]. For 2D or 3D problem, it would be a 2D or 3D array of logarithmically equally spaced 2D or 3D basis functions, similar to what we would have if we had used equally spaced T1, T2, and diffusion coefficients D on their respective logarithmic scales, only that the numbers of these basis functions are much smaller. Because the size of the inversion matrix is much smaller, the computation time is significantly reduced.Another way is to place these basis functions strategically in theappropriate domains of T1, T2, and diffusion coefficient D where proton distributions are likely to occur. Some of the physical constraints, such as T1>T2, can also be imposed during the formulation of the inversion problem, resulting in even faster inversion speed. In this case, the basis functions need not be symmetric with respect to their center peak value. They can be any predetermined shapes obtained experimentally or empirically, such as the measured T2 distributions of heavy oils. If symmetric Gaussian functions are used as the basis functions and placed in strategic regions for inversion, one can also fine tune such approach by varying the location as well as the width of these Gaussian functions in the appropriate domains of T1, T2, and diffusion coefficient D. Such fine tuning can be accomplished by either linear or nonlinear approach. In the linear approach, the search of the best fit is carried out either systematically or randomly over a grid of varied locations and widths. In the nonlinear approach, such search is done by the Levenberg-Marquardt[9] method over location and width. In either case, this can be performed very fast and efficiently because the matrices involved are much smaller.For a (T1, T2) 2D problem, we can have,Kij=e-ti/T2,j, Wkl=1-e-TW,k/T1,l, and i=1,2,Λ,nk,(6)where bik is the i-th echo of the k-th echo train with nk echoes where a wait time of TW,k is used, and there are p preselected T1 and mpreselected T2 equally spaced on their respective logarithmic scales.For a (D, T2) 2D problem, it becomes,(7)where bik is the i-th echo of the k-th echo train with nk echoes where an echo spacing of TE,k is used, and there are q preselected D and m preselected T2 equally spaced on their respective logarithmic scales. When the 2D basis functions are used, Eqs. (6) and (7) become,(8)(9)where the 2D basis functions are defined as:Bjl,sr=Bs(T2,j)Br(T1,l), or Bjh,sr=Bs(T2,j)Br(Dh)(10)and the solution vector is Csr, with Ns<m and Nr<p or q.The extension of the FCD method to (D, T2, T1) 3D problem is straightforward:(11)where bik is the i-th echo of the k-th echo train with nk echoes where a wait time of TW,k and an echo spacing of TE,k are used, and there are ppreselected T1, m preselected T2, and q preselected diffusion coefficient D equally spaced on their respective logarithmic scales. When the 3D basis functions are used, Eq.(11) becomes:(12)where the 3D basis functions are defined as:Bjlh,srv=Bs(T2,j)Br(T1,l)Bv(Dh)(13)and the solution vector is Csrv, with Ns<m, Nr<p, and Nv<q.Since the number of the basis functions is much smaller than the number assumed for each domain parameter of T1, T2, and D in the full blown case, the computation time is significantly reduced. Further implementation of placing finite number of basis functions in strategic locations reduces the computation time even more.2 Examples of FCD ImplementationFig.1 shows results of a simulation of the FCD implementation. Fig.1(a) is the model of a set of T2 distributions which start out as a well-separated two component T2 distribution and gradually merge into a single component T2 distribution. We assume all T2 distributions have an initial amplitude, i.e., fluid content, of 20 porosity units (p.u.). After superimposing a 1 p.u. Gaussian noise on the corresponding T2 echo trains, the inverted T2 distributions are shown in Fig.1(b) through 1(d). Fig.1(b) shows the result of regular SVD inversion, where echo data were compressed into 100 windows and 100 logarithmically equally spaced T2relaxation times were used. It took about 16 s to finish the computation with a MATLAB script file on a 1.86 GHz PC. Fig.1(c) shows the result of using 11 cubic B-splines as the basis functions and SVD for the subsequent inversion. It took only 3 s to complete the calculation, significantly reducing the computation time. Fig.1(d) shows the result of using two Gaussian-shape bumps as the basis functions, where the peak locations and the widths of the Gaussian-shape bumps were searched nonlinearly using Levenberg-Marquardt method[9] and the amplitudes of the bumps were determined by SVD during the iterative process. This approach took less than 2 s, but often the solutions only satisfy local minimum condition. In order to reach the global minimum, a hundred sets of initial conditions were randomly picked to find the smallest local minimum. The whole inversion then took about 12 s. Although the reduction of computation time (i.e., from 16 s to 12 s) is not significant for 1D problem, this approach of nonlinear search using Gaussian-shape bumps will be much faster and more efficient for 2D or 3D problems. Fig.1(e) shows the qualities of fits for different methods, and they are practically the same.When processing a large amount of 2D NMR data from an NMR well logging measurement, the FCD method becomes essential in significantly reducing the computation time. In general, the save in computation time is about an order of magnitude. Fig.2(a) shows an example of using FCD to perform oil volume estimation in a heavy oil field. T rack 1 is the γ-ray, Tracks 2 and 3 are the volume ratio curves for different fluid components, and Tracks 4 and 5 are the T2 distributions derived from regular T2 andFCD inversions, respectively. In Tracks 2 and 3, the gray colored area indicates clay bound water, blue area gives capillary bound water, cyan colored area is water in clean sand formation, and green colored area indicates heavy oil. Without getting into the detail of log analysis, we simply state that the heavy oil section at the bottom of Track 2 is clearly mistyped by regular T2 inversion while the FCD method gives an excellent result using five Gaussian shapes that represent T2 distributions of clay bound water, heavy oil, capillary bound water, and movable water, respectively. Fig.2(b) shows a typical result of inverting 2D NMR maps from an NMR well logging measurement using the FCD method. Track 1 displays volume ratio of different fluid components, Track 2 is the T2 distribution projected from 2D NMR along the T2 axis, Track 3 is the projected diffusion coefficient distribution along the diffusion axis, and Track 4 is the contour plot of 2D NMR maps. The water peak is identified by its diffusion coefficient being around the vertical cyan line in Track 4 which indicates the diffusion coefficient of bulk water at the reservoir temperature. The oil peak shows two components. The light component of the oil is identified by its location being on a D-T2 curve.Fig.1 (a) T2 distribution model. (b) Inverted T2 distribution using simple SVD after superimposing 1 p.u. Gaussian noise. (c) Inverted T2 distribution using cubic B-spline as basis functions. (d) Inverted T2 distribution using Gaussian shapes as basis functions. (e) Comparison of fit qualities of different inversion methodsFig.2 The FCD method produces the same results with significant reductionin computation time without sacrificing the smoothness and accuracy of the T2 distributions. (a) Field example of fluid saturation derived from fluid component decomposition method. (b) FCD method was used to produce 2D NMR maps to differentiate oil from water in a California oil field3 Solution Constraint for a Group of T2 distributionsThis basis function approach can provide regularizing action and suppress oscillations of T2 amplitude along the T2 relaxation time axis. It becomes natural to think if we can use the same approach to constrain the variation of T2 amplitude between different T2 distributions obtained at sequential depths in a drilled well. Frequently, the NMR T2 echo trains we obtained from well measurements are quite noisy. The spurious signals of the initial echoes often result in unwanted short T2 components, leading to large porosity spikes. They also result in dissimilar T2 distributions for the same rock type, preventing us from using the T2 distribution as a rock type indicator. If we can use the basis function approach in the direction of the depth to constrain the solution, we may be able to obtain more reasonable T2 distributions for neighboring depths of the same rock type, thus allowing us to use the T2 distribution to better evaluate the earth formation. For convenience, we shall call this application of FCD as a vertical constraint (VC) along the depth direction as VCFCD.Fig.3 shows the results of the simulation. Fig.3(a) is the model of the earth formation with several layers of different rock types, each with a characteristic T2 distribution, either single peak or double peaks with varying separation. The generated T2 echo trains are superimposed with aGaussian noise and then inverted to obtain the T2 distributions. Fig.3(b) shows result of the regular T2 inversion performed at each depth without having the constraint along the depth direction. One can notice the slight variation of the T2 distribution between neighboring ones of the same rock type. Fig.3(c) shows the result of VCFCD implementation with constraint along the depth direction using 110 B-splines basis functions. One notices that the variation of the T2 distribution between neighboring ones of the same rock type is no longer there, even though there are some irregularities near the bed boundaries.Fig.3 (a) Model of T2 distributions. (b) Inverted T2 distributions using B-spline SVD without vertical constraint. (c) Inverted T2 distributions using B-spline SVD with vertical constraintThe application to log data yields even more striking result. Fig.4 shows the result of one log example, where the left panel shows the result of regular T2 inversion for each depth using cubic B-spline as the basis function, and the right panel shows the result of T2 inversion also using cubic B-spline as the basis function along the relaxation time axis, but with additional constraint along the depth direction using 100 cubic B-spline as the basis functions. The spurious variations of the T2 distributions among neighboring depths, especially at the tails of T2 peaks, are gone. Fig.5 shows the porosity as a function of depth, where the dashed curve, with significant oscillations, corresponds to the left panel, and the solid curve, with a steady variation, corresponds to the right panel of Fig.4. The result indicates a significantly better result when the constraint using basisfunction is implemented along the depth direction.Fig.4 The result of one log example: the left panel shows the result of regular T2 inversion for each depth using cubic B-spline as the basis function, and the right panel shows the result of T2 inversion also using cubic B-spline as the basis function along the relaxation time axis, but with additional constraint along the depth direction using 100 cubic B-spline as the basis functionsFig.5 Comparison of porosities as functions of depth using regular inversion for each depth and constrained inversion along the depth direction. The dashed curve, with significant oscillations, corresponds to the left panel, and the solid curve, with a steady variation, corresponds to the right panel of Fig.4Fig.6 shows a different log example where solution constraint is used along the depth direction. Track 1 shows the porosity as a function of depth when regular T2 inversion for each depth is performed, whereas Track 2 shows when solution constraint is placed along the depth direction. Tracks 3 and 4 show, respectively, the corresponding T2 distributions of Tracks 1 and 2. The improvement of the appearance for T2 distribution for the same rock type is very significant.Fig.6 A log example where solution constraint is used along the depth direction. Track 1 shows the porosity as a function of depth when regular T2 inversion for each depth is performed, whereas Track 2 shows when solution constraint is placed along the depth direction. Tracks 3 and 4 show, respectively, the corresponding T2 distributions of Tracks 1 and 24 ConclusionsWe have described the “Fluid Component Decomposition” method for fast NMR data inversion. In this method, each fluid component embedded in porous media is represented by a predetermined T2 (or T1) shape and a collection of such fluid components can be used to solve 1D NMR inverse Laplace transform problem. Similarly the fluid component can also be represented by a predetermined (D, T2) or (T1, T2) shape for solving 2D NMR inverse Laplace transform problem, or a predetermined (D, T2, T1) distributions for solving 3D NMR inverse Laplace transform problem. These predetermined shapes can be Gaussian, B-spline, or any experimentally or empirically derived functions. From numerical simulation and field examples, FCD method shows that it not only significantly reduces the computation time for NMR data inversion especially for multi-dimensional data sets from oil well measurements, but also improves the smoothness and accuracy of the inverted distributions. We also showed that such method can be used to find a solution constraint for a group of NMR data with sequential well depths where spurious signals frequently result in dissimilar T2 distributions for the same rock type. Acknowledgments： The authors thank the Chevron management for supporting and giving permission to publish this work.References:【相关文献】[1] Carr H Y, Purcell E M. Effects of diffusion on free precession in nuclear magnetic resonance experiments[J]. Phys Rev, 1954, 94(3): 630-638.[2] Meiboom S, Gill D. Modified spin-echo method for measuring nuclear relaxation times[J]. Rev Sci Instrum, 1958, 29(8): 668-671.[3] Dunn K J, Bergman D J, LaTorraca G A. Nuclear Magnetic Resonance: Petrophysical and Logging Applications, Seismic Exploration, vol.32[M]. Oxford: Pergamon Press, 2002. [4] Sun B, Dunn K J. A global inversion method for multi-dimensional NMR logging[J]. J Magn Reson, 2005, 172(1): 152-160.[5] Butler J P, Reeds J A, Dawson S V. Estimating solutions of the first kind integral equations with non-negative constraints and optimal smoothing[J]. SIAM J Numer Anal, 1981, 18(3): 381-397.[6] Liaw H K, Kulkarni R, Chen S, et al. Characterization of fluid distributions in porous media by NMR techniques[J]. AIChE J, 1996, 42(2): 538-546.[7] Miller A, Chen S, Georgi D T, et al. A new method for stimating T2 distributions from NMR measurements[J]. Magn Res Imaging, 1998, 16(5-6): 617-619.[8] Sun B. In-Situ Fluid Typing and Quantification with 1D and 2D NMR Logging[J]. Magn Reson Imaging, 2007, 25(4): 521-524[9] Press W H, Flannery B P, Teukolsky S A, et al. Numerical Recipes[M]. Cambridge: University Press, 1986.。

武汉2024年统编版小学三年级下册英语第2单元暑期作业(含答案)考试时间：100分钟（总分:120）B卷考试人：_________题号一二三四五总分得分一、综合题(共计100题共100分)1. 选择题：What is the capital of the United States?A. New YorkB. Washington D.C.C. Los AngelesD. Chicago2. 听力题：Plants help to keep our _______ clean.3. 听力题：A __________ is a combination of two or more elements chemically bonded together.4. 选择题：What is the smallest unit of life?A. OrganB. TissueC. CellD. Organism5. 填空题：The ________ was a famous figure in the American Revolutionary War.6. 填空题：The _____ (火龙果) is a unique fruit that looks very interesting.火龙果是一种外形非常独特的水果。

7. 选择题：What do we call a person who studies the historical development of ideas?A. Intellectual HistorianB. PhilosopherC. SociologistD. Anthropologist答案: A8. 听力题：The main gas released during fermentation is ______.9. 选择题：What tool do astronomers use to observe distant stars?A. MicroscopeB. TelescopeC. BinocularsD. Camera10. 填空题：Rust is formed when iron reacts with _______. (水)11. 填空题：A ________ (洲际) is a large area of land.12. 选择题：What is the smallest continent?A. AsiaB. AustraliaC. EuropeD. Antarctica答案:B13. 填空题：The ancient Egyptians used hieroglyphics for ______ (书写).14. 选择题：What is the capital city of Brunei?A. Bandar Seri BegawanB. Kuala BelaitC. TutongD. Seria15. 听力题：George Washington was the commander of the Continental ________.16. 听力题：We are having a ___. (family gathering) soon.17. 填空题：We have a ______ (丰富的) curriculum at school.18. 选择题：What do we call a sweet drink made from herbs and spices?A. TeaB. Herbal InfusionC. TisanD. All of the above19. , I take my ________ (玩具名) to the park. I like to ________ (动词) with my friends there. We have a lot of ________ (名词) together. 填空题：Sometime20. 填空题：My favorite game is ______ (棋). It requires a lot of ______ (思考).21. 听力题：The ______ enjoys reading books.22. 填空题：My friend is __________ (勇敢的) and stands up for others.23. 填空题：Gardening can be a rewarding ______ that connects people with nature.(园艺是一项有益的活动，可以将人们与自然联系起来。

小学上册英语第二单元期末试卷(有答案)英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.Earthquakes can occur along fault lines due to ______ stress.2.The __________ (历史的纽带) connects us.3.仿照例子,结合图片及关键词写句子。

4.The chemical symbol for sulfur is _______.5. A _____ is an area with high elevation.6.What do you call the main substance in an experiment?A. VariableB. ControlC. SampleD. Subject答案:C7.Chemical reactions often require _____ to start.8.I can use my toy ________ (玩具名称) to create new ideas.9.What is the name of the famous novel written by George Orwell?A. Brave New WorldB. Moby DickC. 1984D. Animal Farm答案: C10.My sister is a ______. She loves to study animals.11.This girl, ______ (这个女孩), enjoys volunteering at the animal shelter.12.We play ______ (棒球) in the afternoon.13.We have a ______ (丰富的) class schedule.14.The sun is ______ brightly during the day. (shining)15.In summer, the days are long and __________. (温暖的)16.What do we call a device that takes pictures?A. CameraB. ProjectorC. TelevisionD. Computer答案:A17.My pet has a _______ (特殊的) collar with a bell.18.When I talk to my friends, I often use the name __. (当我和朋友聊天时，我常常用名称。

小学上册英语第六单元期末试卷(含答案)英语试题一、综合题(本题有50小题，每小题1分，共100分.每小题不选、错误，均不给分)1 I can ______ (count) to .2 Penguins are birds that cannot ______.3 My friend is a great __________ (听众) and always supports me.4 The chemical symbol for zirconium is _______.5 Many _______ spread their seeds by wind.6 The chemical symbol for rhenium is ______.7 The chemical symbol for gallium is _______.8 What is the main ingredient in bread?A. SugarB. FlourC. RiceD. Salt9 The ancient Egyptians made ______ (木乃伊) as part of their burial practices.10 Which month has Halloween?A. SeptemberB. OctoberC. NovemberD. December答案:B11 What do we call the time of year when flowers bloom?A. WinterB. SpringC. SummerD. Autumn12 A solution that has a low concentration of solute is called a ______ solution.13 A chameleon can shift its color to communicate or ______ (伪装).14 What do you call the process of learning new skills?A. TrainingB. EducationC. PracticeD. All of the above答案: D. All of the above15 What is the name of the famous ancient civilization that built the Great Wall?A. RomansB. GreeksC. ChineseD. Egyptians答案: C16 The porcupine protects itself with its _______ (刺)。

小学下册英语第3单元测验卷(有答案)英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1.The sun is shining ________ today.2.Eclipses happen when one celestial body moves into the _______ of another.3.I enjoy planting _____ (多肉植物).4.My sister enjoys __________ (画画) in her free time.5.What is the capital of Iceland?A. ReykjavikB. OsloC. HelsinkiD. Faroe Islands答案:A.Reykjavik6.I think exercising is important for staying __________.7.My dad enjoys going to the ____ (beach).8.The rabbit is ______ (eating) a carrot.9. A _______ (马) can be very strong.10.The chemical formula for aluminum chloride is ______.11.The stars are _____ bright tonight. (very)12.They are _____ (jumping) over puddles.13.The smallest particle of an element is an ______.14.I love visiting the _______ (地方) because I learn new things every time.15.The ______ (小鸟) sings sweet melodies in the morning ______ (阳光).16. A reaction that produces carbon dioxide is called a ______ reaction.17.The ______ is a season when flowers bloom.18.We are _____ a field trip next week. (going on)19.What is the capital of Nigeria?A. LagosB. AbujaC. KanoD. Port Harcourt答案:B20.My sister is a good ________.21.Metalloids have properties of both ________ and nonmetals.22.The capital of Colombia is __________.23. A chemical reaction can be classified as ______ or endothermic.24.The ____ hops around and has big, floppy ears.25.The bunny's nose twitches with _____ curiosity.26.I enjoy baking ______ (蛋糕) for special occasions.27.Leaves fall off trees in ________ (秋天).28.We are going to the __________ tomorrow.29.The ______ (小鱼) swims in a school to stay safe from predators.30.What is the name of the famous temple in Cambodia?A. Angkor WatB. BorobudurC. ShwedagonD. Taj Mahal答案: A31.Substances that speed up chemical reactions are called _______.32.The _______ (鲸鱼) can dive deep into the ocean.33.The __________ (历史的多元视野) offer fresh insights.34. A _______ helps to measure the amount of pressure exerted on a surface.35.I can ______ (draw) animals.36.The _______ (蜗牛) leaves a trail.37.The chemical symbol for chlorine is ______.38.Goldfish are often kept in ______ (鱼缸) as pets.39.The __________ can provide critical insights into environmental sustainability.40.We visit the ______ (文化中心) for events.41.Acids react with metals to produce _____ gas.42.The raccoon is known for its _______ (灵活).43.The _______ provides a habitat for many insects.44.I usually drink ______ with my meals.45.What is the name of the famous ancient civilization that built the Great Wall?A. RomansB. GreeksC. ChineseD. Egyptians答案: C46.What do you call a baby giraffe?A. CalfB. KidC. PupD. Foal答案: A47.The ______ is the part of a plant that makes seeds.48. A _____ (cactus) is well-adapted to dry conditions.49.The chemical symbol for zinc is ______.50. A ______ (自然保护区) can protect vulnerable species.51.What is the capital city of Russia?A. MoscowB. St. PetersburgC. KievD. Warsaw答案: A52. A solar panel converts sunlight into ______.53.The capital of Georgia is ________ (格鲁吉亚的首都是________).54.The Earth's crust is divided into ______ sections.55.I like to share my stories with my toy ________ (玩具名称).56.The ________ is very lively.57.The chemical formula for -octanol is ______.58. A chemical that reacts with water to produce a gas is called a ______ agent.59.What do you call the main character in a story?A. AntagonistB. ProtagonistC. Supporting CharacterD. Narrator 答案: B60.The first human to reach the South Pole was ______ (阿蒙森).61.The __________ (历史的社会影响) shapes perspectives.62. A _______ is formed when two or more atoms bond together.63.We are going ________ a trip.64.The _______ can change with the seasons.65. A solute is the substance that gets ______ in a solution.66.The cat likes to play with a _______ (猫喜欢玩_______).67.I love to play outside on sunny ______ (日子). It makes me feel very ______ (快乐).68.The dog is _____. (barking/sleeping/jumping)69.The main component of nucleic acids is ______.70.The _____ (火烈鸟) is often found in warm climates.71.Which musical instrument is played with a bow?A. TrumpetB. GuitarC. ViolinD. Flute答案: C72.小貂) is playful and curious. The ___73.ts have evolved to resist ______ and survive in challenging conditions. (某些植物已进化以抵抗病虫害，在艰难的条件下生存。

1.1In recent years the performance requirements for process plant have become increasingly difficult to satisfy. Stronger competition, tougher ( 更加严苛的) environmental and safety regulations ( 法规), and rapidly changing economic conditions have been key factors in the tightening of plant product quality specifications (产品质量规范).A further complication (复杂) is that modern processes have become more difficult to operate because of the trend toward larger, more highly integrated plants with smaller surge capacities (谐振能力) between the various processing units. Such plants give the operators little opportunity to prevent upsets ( 扰乱) from propagating from one unit to other interconnected units. In view of (考虑到，由于) the increased emphasis placed on safe, efficient plant operation, it is only natural that the subject of process control has become increasingly important in recent years. In fact, without process control it would not be possible to operate most modern processes safely and profitably (有利的), while satisfying plant quality standards.近年来，对过程系统的性能改善需求变得越来越艰难. 更为激烈的竞争，更加严格的环境和安全规范，以及快速变化的经济条件都是加强工厂产品质量规范的关键因素更为复杂的情况是，由于现代创造业朝着规模更大,集成度更高的方向发展,而使不同的加工环节之间的应变能力更低, 所以加工过程更难控制近年来，考虑到工业创造逐渐加强的安全、高效需求，过程控制这个课题变得越来越受重视. 实际上，对于大多数现代工业，要满足安全、高效，产品质量的要求，没有控制系统是不可能的.It is assumed that the inlet and outlet flow rates are identical (相同的) and that the liquid density ρ(rho) remains consant, that is, the temperature variations are small enough that the temperature dependence of ρcan be neglected.Under these conditions the volu me V of liquid in the tank remains constant.假设输入和输出流量是相等的，并且液体密度保持恒定，也就是说温度变化足够小，密度对温度的影响可以忽稍不计. 在这些条件下，槽内液体的体积保持恒定Use a larger tank. If a larger tank is used, fluctuations (波动) in Ti will tend to be damped out (阻尼，衰减) due to the larger thermal capacitance of the tank contents. However, increased volume of tankage would be an expensive solution for an industrial plant due to the increased capital costs of the larger tank.Note that this approach is analogous to the use of water baths in chemistry laboratories where the large thermal capacitance of the bath serves as a heat sink ( 散热装置) and thus provides an isothermal (恒温的) environment for a small-scale research apparatus (仪器). 使用一个更大的槽. 如果使用更大的槽，因为更大的热容，Ti 的波动会趋向于衰减. 然而，体积增加使得开支增加，会使工厂系统的解决方案变得更加昂贵.要指出的是这个方法类似于化学实验室中水缸的使用，水缸的大热容量可以看做散热装置，因此可以为小型研究仪器提供一个恒温环境.Note that in feedforward control, the controlled variable T is not measured.在前馈控制中，被控变量T 是没有被测量的.1.2The motivation of using feedback, illustrated ( 说明) by the examples in Section (1), is somewhat oversimplified.In these examples, the use of feedback is shown to be for the purpose of reducing the error between the reference input and the system output.However, the significance of theeffects of feedback in control systems is more complex than is demonstrated by these simple examples.The reduction of system error is merely ( 仅仅) one of the many important effects that feedback may have upon a system. We show in the following sections that feedback also has effects on such system performance characteristics as stability (稳定性), bandwidth (带宽), overall gain (总增益), disturbance (扰动), and sensitivity (灵敏度).第一节事例中，应用反馈的动机有些过于简单。

高二英语科学与技术单选题50题1. The ____ of artificial intelligence has greatly changed our lives.A. innovationB. inventionC. discoveryD. creation答案：A。

解析：本题考查名词辨析。

innovation强调创新、革新，人工智能是一种创新技术，它的创新极大地改变了我们的生活；invention侧重于发明创造出原本不存在的东西；discovery侧重于发现原本就存在但未被发现的事物；creation更多指创造、创作，侧重于艺术等方面的创作，这里说人工智能的创新，所以选A。

2. With the development of ____, we can communicate with people all over the world easily.A. technologyB. scienceC. researchD. experiment答案：A。

解析：本题考查名词。

technology表示技术，随着技术的发展，我们能够轻松地与世界各地的人交流；science指科学，比较宽泛；research侧重于研究；experiment表示实验，这里强调技术发展带来的交流便利，所以选A。

3. The new ____ in the field of space exploration allows us to knowmore about the universe.A. deviceB. methodC. systemD. theory答案：A。

解析：本题考查名词。

device表示设备、装置，在太空探索领域的新设备能让我们更多地了解宇宙；method指方法；system表示系统；theory表示理论，根据题意是新设备起作用，所以选A。

4. The ____ of 5G technology makes the Internet speed much faster.A. applicationB. appearanceC. operationD. function答案：A。

冠夺市安全阳光实验学校广东高明县2017高考英语九月阅读理解课外自练阅读理解。

Beginning college is exciting: new ideas to explore, new challenges to be met and many decisions to be made. Your future begins here. However, you will find college life is different from your previous school environment. Many of us can be easily overwhelmed(压垮) by the details of running a well-balanced life. While some of us may have the know-how, I guess there are more of us who can benefit from learning about the experiences of other who have walked the college halls before you. The following you may find of use about life on campus.1.Plan well. There are so many new things to do at a new college or university, social and academic(学术的). Give yourself time to make new friends and become familiar with the campus, but don’t forget why you are there. Give some time for social activities and manage your time wisely.2.If you don’t have a “system” for planning your time now (likea day time, a computer date book), get one. Most of all, don’t depend on your memory.3.Don’t miss the guidelines, restrictions, rules and regulations of all kinds can usually be found in your student handbook. Consider them well-balanced food for thought. What dates are important? What pieces of paper need to be handed in? What can/can’t you do in your student residence(住处)? Who has authority for what? What do you need to complete to graduate?4.Write the word “STUDY” on the walls of our bedroom and bathroom, and maybe it will help to write it on a piece of paper and stick it on the telephone, TV and the kitchen table. Consider this –you are paying thousands of dollars for courses. You pay every time you have to repeat or replace a course.1. What is the main purpose of the passage?A. To offer advice on college life.B. To explain why college life is exciting.C. To describe the importance of college life.D. To persuade you to go to college ]2. From the passage, we can know .A. one will have more freedom at collegeB. one will make more friends at collegeC. one prepares for one’s future career and life at collegeD. professors at college will provide you with many new ideas3. What is the probable meaning of the underlined word “know-how” (in Paragraph 2)?A. An understanding of how things are going at college.B. A practical knowledge about how to behave and what to do at college.C. College halls where rules and regulations are presented.D. An environment completely different from the one you’re used to.4. According to the passage, college students .A. needn’t learn from those who went to college before themB. should spend as much time as possible on social activitiesC. should have a “system” for planning their timeD. are supposed to repeat or replace at least one course【参考答案】1—4、ACBC2016高考英语阅读理解--政治经济文化类请认真阅读下列短文，从短文后各题所给的A、B、C、D四个选项中，选出最佳选项。

小学下册英语第四单元自测题[含答案]英语试题一、综合题(本题有100小题，每小题1分，共100分.每小题不选、错误，均不给分)1. A green _______ can be very refreshing.2.The __________ is a large forest in Germany. (黑森林)3.bay) is a body of water partially surrounded by land. The ____4. A _______ is a reaction that releases heat.5.My cousin is very __________. (幽默)6. A _______ is formed when two or more atoms bond together.7.I enjoy visiting the ______ (市集) to find unique handmade items.8.What is the name of the story about a girl who befriends seven dwarfs?A. CinderellaB. Snow WhiteC. RapunzelD. Aladdin答案:B9. A ____ is a small insect that can be found in gardens.10.I enjoy spending time at the ________ (图书馆), where I can find many interesting ________ (书籍).11.What instrument is played with keys?A. GuitarB. DrumsC. PianoD. Flute答案:C12. A ______ is a type of model used in science.13.The _____ (植物观赏) attracts many visitors.14.The chemical formula for brassylic acid is ______.15.I enjoy playing with my ________ when it rains.16.During break time, I enjoy playing ______ (捉迷藏) with my classmates. It’s always a good laugh.17.I can imagine different worlds with my ________ (玩具名称).18.The __________ (历史的深刻反思) influences decisions.19.What do we call a place where you can see many different kinds of animals?A. ZooB. AquariumC. MuseumD. Park答案:A20.The process of separating mixtures is called ______.21.My mom reads me . (我妈妈给我读。