Existence of Positive Solution to a Singular System of Nonlinear Fractional Differential Equatio
存在的问题的英语短语

存在的问题的英语短语IntroductionIn our daily lives, we face numerous problems ranging from small to significant issues. Issues can be personal or occur in society, and these problems need to be addressed to improve the situation. Identifying problems is an essential step towards finding solutions to them. The existence of problems is an indication that something is wrong and needs rectification. This paper aims to discuss various phrases related to the existence of problems.Identifying a problemIdentifying a problem is the first step towards finding the solution. The following phrases can be used to express the existence of a problem:1. There is a problemThis phrase indicates a general problem in a situation, but the complexity and nature of the problem are yet to be described.2. We have a problemThis phrase suggests a problem that requires immediate attention and solving.3. The problem is obviousThis phrase indicates an evident problem that everyone can see and is often directly linked to an action.4. We are facing an issueThis phrase indicates that the problem is not easy to solve, and several factors must be considered before taking action.Causes of problemsVarious factors contribute to the occurrence of problems. Identifying the cause of the issue is essential to finding the right solution. The following phrases can be used to express the causes of problems:1. The problem stems fromThis phrase highlights the underlying cause contributing to the problem and often helps to find a solution for the problem.2. The problem is a result ofThis phrase implies that the problem has arisen following a series of actions or events.3. The problem is due toThis phrase suggests that the problem has occurred due to a specific factor or circumstance.4. The issue is a consequence ofThis phrase indicates that the problem is a result of something that happened previously.Solution to problemsFinding a solution to a problem is crucial to improve the situation. The following phrases can be used to express potential solutions to problems:1. The solution lies inThis phrase indicates that the answer to the problem can be found in a specific action or decision.2. We need to explore all possible solutionsThis phrase suggests that various solutions should be explored and evaluated to find the right one.3. We must take steps toThis phrase highlights the need to take specific actions towards the solution.4. The answer to the problem isThis phrase indicates that the solution to the problem has been found.ConclusionThe existence of problems in society poses significant challenges; However, identifying and finding solutions to these problems can help make the world a better place. The phrases mentioned above related to the existence of problems can help in identifying, understanding, and solving the issue. By using these phrases, we can communicate the existence of a problem more effectively and help find potential solutions.。
小学上册第7次英语第三单元期末试卷

小学上册英语第三单元期末试卷英语试题一、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.What do we call the main character in a story?A. ProtagonistB. AntagonistC. HeroD. Villain2.Which season comes after spring?A. WinterB. SummerC. FallD. AutumnB3.I love the way my __________ (玩具名) __________ (动词).4.What is the name of the tallest building in the world?A. Burj KhalifaB. Empire State BuildingC. Eiffel TowerD. CN Tower5.The manatee is a gentle _______ (巨兽).6.My ________ (兄弟) is learning to ride a bike this summer.7.My mom loves __________ (促进社区发展).8.What is the process of converting a liquid into a gas called?A. MeltingB. FreezingC. EvaporationD. CondensationC9.The tree is home to many ______.10.The ________ was a famous naval battle during World War II.11.My friend is a ______. He loves to explore.12.What is the largest land animal?A. LionB. TigerC. ElephantD. GiraffeC13.The concept of a multiverse suggests the existence of _______ universes.14.We should _______ (努力) to make a difference.15. A __________ is a type of mammal that lays eggs.16.The atomic number tells us the number of ______ in an atom.17.The ________ (茎) transports nutrients.18.The study of matter and its changes is called ______.19.My pet parrot can _________ (说话).20.The boy has a cool ________.21.The ____ has big wings and can glide through the air.22.The __________ (历史的价值认知) shape our identities.23.What is the name of the large ocean between Africa and Australia?A. Atlantic OceanB. Indian OceanC. Arctic OceanD. Pacific Ocean24.The __________ is the line that divides the Earth into eastern and western hemispheres.25.The capital of Equatorial Guinea is ________ (赤道几内亚的首都是________).26.What is the term for the gradual increase in brightness of a supernova?A. Light CurveB. Brightness IncreaseC. Magnitude ShiftD. Luminosity Change27.I can ______ (发展) my skills through practice.28.My __________ (玩具名) helps me to relax when I __________ (动词).29.The owl's big eyes help it see in the _________. (黑暗)30.My ________ (玩具名称) is an integral part of my daily routine.31.My cousin is very __________. (有趣)32.The classroom is _____ and bright. (clean)33.Bubbles forming in a solution may indicate a ________ reaction.34. A _______ can help to visualize the concept of thermal energy.35.cultural exchange) enhances understanding among groups. The ____36.The __________ was a time of great technological advancement. (工业革命)37.I can ______ (保持) a positive outlook in life.38.What is the primary color of the sun?A. BlueB. YellowC. PurpleD. Green39.The teacher is ___ the children. (guiding)40. A __________ is the measure of how much solute is present in a solution.41.What is the name of the period before history was written?A. PrehistoryB. Ancient historyC. Medieval timesD. Modern historyA42.My favorite singer is _______ (某个歌手).43.What is the name of the first human to walk on the moon?A. Neil ArmstrongB. Buzz AldrinC. Michael CollinsD. Yuri Gagarin44.What is the main source of energy for plants?A. SoilB. WaterC. SunlightD. Air45.The _____ (窗台) has flowers.46. A solution is formed when a solute dissolves in a _____.47.I can ______ (提升) my creativity through art.48.The chemical formula for magnesium sulfate is _______.49. A _____ (植物信息平台) can enhance knowledge sharing.50.What is the capital of Bangladesh?A. KolkataB. DhakaC. ChittagongD. SylhetB51.The tortoise moves slowly but can live for a very ________________ (长) time.52.What do we call the process of converting sunlight into energy?A. PhotosynthesisB. RespirationC. FermentationD. CombustionA53.What do we call the process by which plants make their food?A. DigestionB. PhotosynthesisC. RespirationD. GerminationB54. A __________ is a low-lying area that can be flooded.55. A frog can jump _______.56.My dad likes to ______ (烹饪) on weekends.57.The chameleon can change to match its _______ (环境).58.What is the capital of the Netherlands?A. AmsterdamB. RotterdamC. UtrechtD. The HagueA59.The _____ (野生动植物) depend on local plants for survival.60.She is painting a ___. (mural)61.In geography, a __________ is a large landmass.62.The __________ can be used to classify different types of rocks.63.My pet responds to the name ____. (我的宠物对名字____有反应。
EXISTENCE AND GLOBAL ATTRACTIVITY OF PERIODIC SOLUTIONS TO A PREDATOR-PREY SYSTEM WITH DELAYS AN

1
Introduction
In [1], May introd u ced th e following p red ator-pre y sy ste m � h dH ( t ) H (t − τ ( t)) i � � = r H (t ) 1 − − αH (t ) P ( t) , dt K � � dP ( t ) = − bP ( t) + β P ( t ) H ( t − σ ( t )) , dt
An n. of D iff. Eqs . 24:2(2008) , 197-207
EXISTENCE AND GLOBAL ATTRACTIVITY OF PERIODIC SOLUTIONS TO A PREDATOR-PREY SYSTEM WITH DELAYS AND IMPULSES ∗ †
A bs tra t
B y usin g Ga ines an d M aw hin ’s c ont inua tio n t heo rem of co incidence deg ree theo ry a nd co nstruct ing L yapu nov funct io na ls, a se t o f ea sily verifiable suffi cient co nditio ns a re derived for t he exist ence a nd g lo ba l a t trac tivity o f a po sitive perio dic so lut io n t o a predat o r-prey syst em with dela ys a nd impu lses. Key wo rds perio dic so lut ion; im pulsive e qu at io n; c oincidence deg ree t heo ry; globa l a t trac tivity 20 00 M athem atic s Sub jec t C lassific ation 3 4 K13 ; 92 D2 5
EXISTENCE AND UNIQUENESS OF SOLUTIONS TO STOCHASTIC DIFFERENTIAL EQUATION WITH RANDOM COEFFICIEN

Su ppo rt ed by t he N at io na l N a t ura l S cienc e Fo unda tion of C hina ( N o.10 7 01 02 0 ). M anuscript received M ay 1 4, 2 00 9
400
No.4
G .X. Hu, etc., SD E WITH RANDO M CO EFF ICIE NTS
2
Many resu lts on th e existen ce an d un iq ue ne ss of solution s cou ld be fou nd in [2-3] an d re feren ces the rein. Motivate d by th e work of Av ne r Frie dm an [4], wh ich gave th e sim ple pro of of th e e xisten ce and u niq uen ess the ore m for SD Es with rand om coe ffic ie nts, u nd er c ond itions (2) and (3), in this p ap er, we con side r the e xiste nc e and u niqu en ess of solu tions to the followin g SD E with rand om c oeffi cien ts:
T his pa per m a inly dea ls w it h a st ocha stic different ia l equ at io n ( SDE) w it h ra ndo m co effi cient s. Suffic ient co ndit ions w hich gua ra nt ee th e exist ence a nd un iqueness of solutio ns t o the equat io n a re give n. Key wor ds sto cha st ic diff ere nt ial equat ion; ra ndo m co effi cients; exist ence a nd uniqueness 20 00 M athem atic s Sub ject C lassific ation 6 0 H1 0 ; 3 4 A1 2
THE EXISTENCE OF POSITIVE SOLUTIONS TO BOUNDARY VALUE PROBLEM OF SECOND ORDER DIFFERENTIAL EQUAT

10
No.1
J. Dai, et c., P OSITIVE SO LUTIONS TO BVP
11
2
Main Results
Th e fi xe d p oint in de x h as the followin g p rop erties.
Lemm a 1 Let K be a closed con vex set in a Banach space E , D be a boun ded open set such t hat D k := D ∩ K �= ∅ an d T : D k → K be a completely con tin uou s map . S uppose that x �= T x for all x ∈ ∂ D k . Then we obtai n the follow ing conclu sion s: (D1 )( Existen ce) if i ( T, D k , K ) �= 0 , th en T has a fixed poin t in D k ; (D2 )( Normalizat ion) if u 0 ∈ D k , t hen i( b u , D k , K ) = 1 , where b u( x ) = u 0 , for x ∈ D k ; (D3 )( Homot opy ) let h : [0 , 1] × D k → K be a complet ely cont inu ous map such that x �= h (t, x ) for x ∈ ∂ D k an d t ∈ [0 , 1] , then i( h (0 , · ) , D k , K ) = i (h (1 , · ) , D k , K ) . For fu rthe r in form ation on the classical fi xe d p oint in de x for comp letely c ontinuou s map s, see [7]. Now we state an d p rove a ne w fixe d p oint the orem in C 1 [0, 1] sp ace usin g th e p rope rtie s of th e fi xe d p oint in de x. Theorem 1 Let E = C 1 [0 , 1] be en dow ed w ith t he no rm � x� = max{� x � 0 , � x� � 0 } , wh ere � x � 0 = max | x ( t) | , an d P = { x ∈ E | x (t ) ≥ 0 , t ∈ [0 , 1] } be a co ne in E . S uppose
几类生态学模型的定性分析

妒㈣2而,
表示捕食者的捕食量随食饵的增加而上升,直到饱和水平.当食物多时,由于捕食者饥饿
程度降低而出现负加速.此类功能反应多见于无脊椎动物和某些食肉鱼类.
Holling-III型响应函数为
ax2
,、
妒【zJ
2—1+—bx2,
这类功能反应为具有复杂行为的脊椎动物所特有.在食物较少时,学习捕捉,随着食物的
§1.1 相关生态学微分方程模型的背景和发展概况
设食饵种群的密度为z,捕食者种群的密度为Y,捕食者不存在时,食饵按指数方式增 长,捕食者在无食饵时,按指数方式减少.如果这两个种群生活在同一空间,由于捕食作 用,食饵的增长率随着捕食者的增多而下降,而捕食者的增长率随着食饵的增多而上升. 于是经典的Lotka-Volterra捕食模型可以写成
In Chapter 5,a structured—stage predator-prey model with cross-diffusion is considered.The existence of non-constant positive solutions is obtained.The result shows that the cross-diffusion can create Turing Pattern.
,面d27=(rt-btx-cly)% 1面dy=r2--c2》
Holling在实验研究的基础上,对不同类型的捕食者提出了三种不同的响应函数. Holling-I型响应函数为
妒cz,={孑’z0<三x。,≤口,
2
东南大学博士学位论文
多见于滤食性捕食动物(如多数软体动物).
Holling-II型响应函数为
absolute values of cross-diffusion coefficients are small enough and the coefficients satisfy some conditions.At the same time,the existence of positive solutions is gained when the two cross- diffusion coefficients are negative constants with bifurcation theory.
EXISTENCE AND MULTIPLE EXISTENCE OF POSITIVE SOLUTIONS TO SECOND-ORDER m-POINT BOUNDARY VALUE PR

αi x � (ξ i ) ,
x (1) =
i=1
m −2 X
β i x (ξ i ) ,
(1.4)
∗ T he wo rk w as sp onso red by the N a tu ra l Science Fo unda t io n of A nhui Ed ucat iona l Dep artm ent (KJ2 00 9 B1 00 ; KJ20 10 B1 6 3) . † M anuscript received July 29 , 20 08 ; Revised Ma rch 21 , 2 0 09
234
No.2
L. Yang, etc., BVP O N TIME SCA LE S
235
wh ere ξi ∈ [0 , ρ (1)]T , 0 < ξ1 < ξ2 < · · · < ξm − 2 < ρ (1) an d the followin g con ditions holds: (C 1 ) f ∈ C ([0 , + ∞ ) , [0 , +∞ )) an d th e f un ction a is le ft de nse con tin uou s on [0,1] and is R1 non ne gative with 0 a( s) � s existing as a strictly p ositive re al numb e r; m −2 m −2 P P (C 2 ) αi ≥ 0, β i ≥ 0 , i = 1 , 2 , · · · , m − 2 satisfy 0 < αi < 1 an d 0 < βi < 1.
拥有乐观生活态度的重要性英语作文

拥有乐观生活态度的重要性英语作文全文共3篇示例,供读者参考篇1The Significance of Embracing an Optimistic Outlook in LifeAs students, we are constantly bombarded with challenges, deadlines, and expectations that can easily overwhelm us if we allow them to. However, I firmly believe that maintaining a positive mindset amidst these trials is not only beneficial but crucial for our overall well-being and success. An optimistic attitude is a powerful tool that can transform our lives, enabling us to tackle obstacles with resilience, find joy in the journey, and ultimately achieve our goals.One of the most profound advantages of having a positive outlook is its impact on our mental health. When we approach life with a glass-half-full mentality, we are better equipped to cope with stress and anxiety. Instead of dwelling on setbacks or dwelling on what could go wrong, we choose to focus on the possibilities and potential solutions. This shift in perspective allows us to maintain a sense of control and empowerment, rather than feeling helpless or overwhelmed.Furthermore, a positive attitude fosters a growth mindset, which is essential for personal and academic development. When we embrace challenges as opportunities for growth, we are more likely to persist in the face of adversity and learn from our mistakes. This resilience enables us to continuously improve and expand our knowledge and skills, ultimately setting us up for long-term success.Beyond the individual benefits, an optimistic outlook can also positively influence our relationships and interactions with others. Our positivity can be contagious, inspiring those around us to adopt a similar mindset. This creates a supportive and uplifting environment, where we can collectively overcome obstacles and celebrate each other's achievements. In group projects or team-based activities, a positive attitude can foster collaboration, open communication, and a shared sense of purpose, leading to more productive and rewarding experiences.Additionally, an optimistic perspective can open doors to new opportunities and experiences. When we approach life with an open mind and a willingness to embrace change, we become more receptive to possibilities that may have otherwise been overlooked. This curiosity and adaptability can lead us downunexpected paths, exposing us to diverse perspectives and enriching our lives in ways we could never have imagined.However, it is important to acknowledge that maintaining a positive attitude is not always easy, especially in the face of significant challenges or setbacks. Negative thoughts and emotions are a natural part of the human experience, and it is unrealistic to expect ourselves to be consistently upbeat. The key is to develop resilience and coping mechanisms that allow us to process these feelings in a healthy manner, while still maintaining an overall optimistic outlook.One effective strategy is to cultivate gratitude and appreciate the small joys in life. Taking a moment to reflect on the things we are grateful for, whether it's a supportive friend, a beautiful sunset, or a hard-earned achievement, can shift our focus away from negative thoughts and remind us of the positives in our lives. Additionally, practicing self-care through activities like exercise, meditation, or engaging in hobbies we enjoy can help us recharge and maintain a balanced perspective.It is also important to surround ourselves with a supportive network of individuals who share our positive outlook or inspire us to maintain it. Seeking out like-minded peers, mentors, or rolemodels can provide invaluable encouragement and motivation, especially during times of struggle or self-doubt.In conclusion, embracing an optimistic attitude is not only a valuable asset but a necessity for navigating the challenges and opportunities that life presents to us as students. By cultivating a positive mindset, we equip ourselves with the resilience, growth mindset, and adaptability required to thrive academically and personally. While maintaining optimism is not always easy, it is a skill that can be developed and nurtured through conscious effort and support. As we embark on our academic journeys, let us embrace the power of positivity and unlock the countless possibilities that await us.篇2The Importance of Cultivating a Positive Life AttitudeAs a student, life can often feel like an uphill battle. We are constantly faced with challenges, whether it's acing that next big test, juggling extracurriculars, or figuring out our future plans. In the midst of all these pressures, it can be easy to lose sight of the bigger picture and get bogged down by negativity. However, I've come to realize that maintaining a positive attitude is key to not just surviving, but truly thriving during these formative years.At its core, a positive attitude is about perspective. It's the ability to approach life's inevitable obstacles with resilience, optimism, and a solution-oriented mindset. When faced with a setback, those with a positive outlook don't waste time wallowing in self-pity or making excuses. Instead, they ask themselves, "Okay, what can I learn from this experience, and how can I improve moving forward?"This mental framework proves invaluable in the academic arena. Think about it – how many times have you totally bombed a test or assignment, only to get consumed by negative thoughts like "I'm just not smart enough" or "I'll never get this material"? With a positive attitude, you're able to refocus and treat that poor performance not as a permanent state, but as an opportunity to identify your weaknesses and create a plan to overcome them. You study smarter, seek out extra help, and approach the next assessment with renewed determination and confidence.But the benefits of positivity extend far beyond just grades. Having an optimistic disposition can improve virtually every aspect of your life as a student. It makes you more resilient in the face of rejection, better able to cope with stress, and more proactive about taking care of your mental and physical health.Positive people are also more fun to be around – their energizing outlook and refusal to complain about trivial matters make them a delight in group settings. This can translate to stronger friendships, better teamwork, and a more fulfilling social experience overall.Cultivating a positive mindset takes continuous work and self-awareness. It's about catching yourself when you start spiraling into negativity and consciously reframing your perspective. Maybe your first thought after a poor performance is "I'm such a failure." But then you stop, take a breath, and rephrase it as "That didn't go as planned, but it's an opportunity to learn and grow." Over time, this mental shift becomes more natural and automatic.It also helps to proactively build habits and routines that reinforce positivity. This could mean starting each morning with positive affirmations, scheduling mood-boosting activities into your day, or simply surrounding yourself with positive people who radiate a can-do spirit. I've found that even small things, like making my bed right after waking up, can instill a sense of discipline and control that puts me in a positive-minded headspace.Of course, no one is positive 100% of the time – that's humanly impossible. We all have moments of frustration, sadness, and negativity. The key is not letting those temporary emotions become your default state. Don't beat yourself up for having negative thoughts; instead, treat them as passing clouds, and refocus your energy on shifting your perspective back to a positive one.Looking back at my academic journey so far, I can clearly see how cultivating an attitude of positivity has benefited me tremendously. The times when I've felt most overwhelmed, stressed, and ready to give up have invariably been the times when I slipped into a cycle of negative thinking. Conversely, my greatest accomplishments and personal growth have stemmed from a steadfast positive outlook that helped me power through difficulties with resilience and determination.Ultimately, our attitude is one of the few things in life that we have full control over. We can't always control our circumstances or the behavior of others, but we can control how we choose to perceive and respond to them. By making the intentional choice to approach life with positivity, optimism and a solution-focused attitude, we take charge of our own happiness and open the door to limitless growth and fulfillment.So to all my fellow students out there – I urge you to make positivity a priority. It's a mindset that will carry you through academic challenges, open doors to incredible opportunities, and ensure that you don't just get by, but truly thrive during these remarkable years. The power of a positive outlook is one of the most invaluable lessons I've learned, and I have no doubt it will continue to shape my future successes.篇3The Power of Optimism: Embracing a Positive Mindset for a Fulfilling LifeAs a student navigating the tumultuous journey of academic pursuits and personal growth, I have come to realize the profound impact that our mindset can have on our overallwell-being and success. In an era where stress, anxiety, and negativity seem to pervade every aspect of our lives, cultivating an optimistic outlook has become not just a luxury but a necessity. Embracing a positive life attitude is a powerful catalyst that can transform our experiences, unlock our full potential, and pave the way for a more fulfilling and rewarding existence.The importance of optimism cannot be overstated, as it serves as a potent force that propels us forward, even in the faceof adversity. When we approach challenges with a positive mindset, we are better equipped to overcome obstacles and find creative solutions. Instead of dwelling on the problems, optimists focus on the possibilities, allowing them to see opportunities where others might only see roadblocks. This outlook empowers us to take calculated risks, embrace new experiences, and continuously grow and evolve.One of the fundamental benefits of optimism is its ability to foster resilience. Life, as we all know, is a constant ebb and flow of ups and downs, triumphs and setbacks. It is during the most challenging times that an optimistic attitude truly shines. Optimists possess an unwavering belief in their ability to bounce back from failures and learn from their mistakes. They view setbacks as temporary hurdles rather than permanent roadblocks, and this mindset enables them to persevere and ultimately emerge stronger and wiser.Moreover, optimism has a profound impact on our mental and physical well-being. Research has consistently shown that individuals with a positive outlook tend to experience lower levels of stress, anxiety, and depression. This, in turn, can lead to improved sleep quality, enhanced immune function, and a reduced risk of developing chronic health conditions. Bycultivating an optimistic perspective, we not only nurture our emotional well-being but also contribute to our overall physical health and longevity.In the realm of academics, optimism can be a game-changer. Students who approach their studies with a positive attitude are more likely to embrace challenges, persist in the face of obstacles, and remain motivated throughout the learning process. An optimistic mindset fosters a growth mindset, which is the belief that our abilities and intelligence can be developed through dedication and hard work. This mindset encourages us to embrace learning opportunities, seek feedback, and continuously strive for improvement, ultimately leading to better academic performance and personal growth.Furthermore, optimism plays a crucial role in interpersonal relationships and social interactions. Individuals with a positive attitude tend to be more approachable, likable, and attractive to others. They radiate a contagious energy that can uplift those around them, fostering stronger connections and more meaningful relationships. In a world where social support is invaluable, cultivating an optimistic outlook can pave the way for a robust network of friends, mentors, and allies who can provideguidance, encouragement, and companionship along our life's journey.It is important to acknowledge that maintaining an optimistic perspective is not always easy, and there may be times when we find ourselves succumbing to negative thoughts and emotions. However, with practice and conscious effort, we can train our minds to shift towards a more positive outlook. Simple practices such as gratitude journaling, mindfulness meditation, and surrounding ourselves with positive influences can help cultivate an optimistic mindset.In conclusion, the importance of having an optimistic life attitude cannot be overstated. It is a powerful force that can transform our experiences, empower us to overcome challenges, foster resilience, and contribute to our overall well-being. By embracing a positive mindset, we not only unlock our full potential but also pave the way for a more fulfilling and rewarding life journey. As students and individuals striving for growth and success, it is imperative that we nurture optimism and harness its transformative power to create a life filled with happiness, purpose, and endless possibilities.。