英语流利说Level4 Unit1 Part3 -Dental Problems&Internal Organs

1. 英语流利说Level4 Unit1 Part3 -Dental Problems&Internal Organs

A dental cavity is a hole in the tooth.牙洞是牙齿上的一个洞。
  
 A cavity is caused by bacteria in the mouth.口腔是由口腔中的细菌引起的。
  
 Brushing your teethfrequently and regularly canhelp preventcavities.频繁的且有规律的刷牙有助于预防蛀牙。
  
 A crackedtooth can be caused by biting down on something hard.牙齿破裂可能是咬硬东西造成的。
  
 Dentists treat a cracked tooth by covering it with a crown.牙医用牙冠覆盖裂开的牙齿来治疗（临床）。
  
 A dental X-ray is a picture of your teeth and gums.牙齿x光片是你牙齿和牙龈的照片。
  
 An x-ray shows what can't be seen on the surface of the teeth and gums.x光片显示牙齿和牙龈表面看不到的东西。
  
 Braces are used by dentists to straighten teeth over a period of years.牙套被牙医使用矫正牙齿已经很多年。
  
 Though braces are usually for children, they can also be used for adults with crooked teeth.虽然牙套通常是给孩子用的，他们（牙套）也可以给牙齿歪的成年人使用。
  
 To extract a tooth, means to remove it from the mouth.拔除牙齿，就是把牙齿从嘴里拔出来
  
 Dentists have to pull hard to extract a tooth.牙医必须使劲拔牙
  
 Dentists often inject something into the gum to block the pain during the extraction process.牙医经常在拔牙的过程中往牙龈里注射一些东西来止痛
  
 Braces are used on people with crooked teeth or after an injury.牙套用于牙齿弯曲或受伤后的人。
  
 The heart pumps blood to all parts of the body through a system of arteries and veins.心脏通过动脉和静脉系统将血液输送到身体的各个部位。
  
 It's located in the chest, between the lungs, and beats about once per second.它位于胸腔，在两肺之间，大约每秒跳动一次。
  
 The kidneys remove waste and toxins from the blood.肾脏排出血液中的废物和毒素。
  
 They are bean shaped organs and are about 10 centimeters long and 6 centimeters wide.它们是豆形的器官（脏器），长约10厘米，宽约6厘米。
  
 The lungs exchange oxygen from the air with carbon dioxide from the blood.肺把空气中的氧气和血液中的二氧化碳交换。
  
 They expand when inhaling air, and contract when exhaling air.它们吸入空气时膨胀，呼出空气时收缩。
  
 The stomach is below the heart, and it's part of the digestive system.胃在心脏下面，它是消化系统的一部分。
  
 It usesacidstodigestfood beforepassingit to the small intestine.在食物进入小肠之前，它利用酸来消化食物。
  
 The bladder is a balloon shaped organ that collects urine from the kidneys.膀胱是一个气球状的器官，从肾脏收集尿液。
  
 In an adult, the bladder can hold about half a liter of urine.成年人的膀胱可以容纳大约半升的尿液。

2. 英语流利说 Level6 Unit3 Part2 Listening Infections Diseases 2

1.Now, a century later, we have  flu vaccines  that have reduced the  severity  of epidemics.
  
  现在，一个世纪后，我们有了流感疫苗，可以降低流行病的严重程度。
   
  
  flu vaccines
   
  
 流感疫苗;感冒疫苗
  
  severity 
  
 英 [sɪ'verətɪ]   美 [səˈvɛrɪti] 
  
 n.严重;严格;严谨;严厉的对待
  
 2.These vaccines need to be updated every year because the virus changes and new  strains   emerge .
  
 因为病毒的变化和新菌株的出现，这些疫苗每年都需要更新。
  
 strains: 菌株
  
  emerge: 
  
 英 [iˈmɜ:dʒ]   美 [iˈmɜ:rdʒ] 
  
 vi.出现，浮现;暴露;摆脱
  
 3.What researchers fear is that a new strain of the virus will develop and cause another pandemic.
  
 研究人员担心的是，一种新的病毒株会发展并引起另一场大流行。
  
 4.Once an  outbreak  occurs, transmission of the disease will be even faster than before.
  
 一旦爆发，疾病的传播将比以前更快。
  
  outbreak 
  
 英 [ˈaʊtbreɪk]   美 [ˈaʊtˌbrek] 
  
 n.（战争，怒气等的）爆发;突然发生
  
 vi.爆发
  
 5.An  unintended  consequence of our improved transportation system will be the speed at which an epidemic can spread.
  
 一个意想不到的后果是，我们改进的运输系统的速度将是流行病传播的速度。
  
 unintended
  
 英 [ˌʌnɪnˈtendɪd]   美 [ˌʌnɪnˈtɛndɪd] 
  
 adj.非故意的，无意识的
  
 6.Experts predict that the public health systems will be  overwhelme d and unable to react quickly enough.
  
 专家预测，公共卫生系统将不堪重负，无法迅速作出反应.
  
  overwhelm 
  
 英 [ˌəʊvəˈwelm]   美 [ˌoʊvərˈwelm] 
  
 vt.压倒;淹没;压垮;覆盖
  
 1.So the best  defense  will be to prevent an outbreak from occurring. 
  
 因此，最好的防御措施是防止疫情爆发。
  
  defense 
  
 英 [dɪ'fens]   美 [dɪˈfɛns] 
  
 n.(D-)（美国）国防部，防卫，防卫物
  
 vt.谋划抵御
  
 2.This will require global cooperation and the sharing of data.
  
 这需要全球合作和数据共享。
  
 3.It may also require changes in how humans  interact  with animals.
  
 它还可能需要改变人类与动物的互动方式。
  
 4.Animals such as birds and pigs carry viruses that may  mutate  into a strain that can infect humans.
  
  mutate 
  
 英 [mju:ˈteɪt]   美 [ˈmju:teɪt] 
  
 vt.& vi.变异;突变;改变;（使某物）变化
  
 5.Such a new strain could lead to another pandemic well before a new vaccine could be developed.
  
  well before:之前 
  
 6.Since diseases and epidemics don't stop at  national boarders , this is a global issue requiring global action.
  
  national boarders：国籍 
  
 7.The threat of a global epidemic is another example of why we must learn to live together.

3. 四：英语流利说Level1-Unit1-Part4（中英文版）

L1-U1-P4-1 Listening :People  人 & Cities城市 
  
 This is Dan.
  
 Hello, my name is Dan.
  
 Dan is a man.
  
 I come from the US.
  
 This is Tina.
  
 Hi, my name is Tina.
  
 Tina is a woman.
  
 I come from China.
  
 This is Ben.
  
 He is from Canada.
  
 He isn't from the US. 他不是美国人。
  
 This is Lisa.
  
 She comes from the US.
  
 She and Dan are from the US. 她和丹来自美国。
  
 They come from the same country.
  
 Here are three cities.
  
 This city is San Francisco. 这个城市是旧金山。
  
 This city is Beijing. 这个城市就是北京。
  
 This city is London. 这个城市是伦敦。
  
 San Francisco is in the US. 旧金山在美国。
  
 Beijing is in China. 北京在中国。
  
 London is in England. 伦敦在英国。
  
 Tina is from China.蒂娜来自中国。
  
 She lives in Beijing. 她住在北京。
  
 Ben is from Canada. 本来自加拿大。
  
 He lives in Toronto. 他住在多伦多。
  
  L1-U1-P4-2 Vocabulary  ：Daily Actions & Body Parts日常活动和身体部位 
  
 Go in to the bathroom. 去洗手间。
  
 Come out of the bathroom. 从浴室出来。
  
 Go in to the elevator. 进电梯。
  
 Come out of the elevator. 从电梯里出来。
  
 Wait for the elevator. 等电梯。
  
 Here are two hands. 这里有两只手。
  
 This is a foot. 这是一只脚。
  
 Here are two feet. 这是两只脚。
  
 This is an arm. 这是一只胳膊。
  
 This is a leg. 这是一条腿。
  
 Go up the stairs. 上楼去。
  
 Go down the stairs. 下楼梯。
  
 Put up your hand.
  
 Put down your hand.
  
 Open the book.
  
 Close the book.
  
    
  
  L1-U1-P4-3 Vocabulary : Daily Actions & 
  
 Weather 天气 
  
 Turn left. 向左转。
  
 Turn right. 向右转。
  
 Go straight.直走
  
 Stop. 停止。
  
 Turn around.转身
  
 sunny weather阳光明媚的天气
  
 rainy weather多雨的天气
  
 cloudy weather多云的天气
  
 cold weather寒冷的天气
  
 hot weather炎热的天气
  
  L1-U1-P4-4 Dialogue:Greetings  问候 
  
 A: Hi, Tina. 嗨，蒂娜。How are you
  
 today?你今天好吗？
  
 B: I'm fine, thanks. 我很好，谢谢。 How
  
 are you?你好吗？
  
 A: I'm fine. 我很好。 It's nice
  
 to see you.很高兴见到你。
  
 Listen carefully: I am = I'm仔细听：I am=I'm
  
 A: Hello, is this Tina? 喂，是蒂娜吗?
  
 B: Hi, yes, this is Tina. 嗨，是的，我是蒂娜。Who is this?这是谁?
  
 A: It's Dan. 我是丹。
  
 B: Oh, hi Dan哦，嗨，丹how are you
  
 today?你今天好吗?
  
 A: I'm fine, thanks. 我很好,谢谢。 How are you?你好吗?
  
 B: I'm fine. 我很好。
  
 B: Hi, Dan嗨，丹how's the weather there?那里天气怎么样?
  
 A: It's fine. 很好。It's sunny
  
 and warm.天气晴朗而温暖。
  
 B: Good, the weather is good here, too. 好，这里的天气也很好。
  
 Ben: How is the weather today? 今天天气怎么样?
  
 Lisa: It's raining. 下雨了。
  
 Ben: Really? It's sunny here. 真的吗?这里的阳光明媚。
  
 Lisa: Well, have a good day. 祝你今天愉快。
  
 Thanks, you, too. 谢谢，你也是。
  
 Listen carefully: How is or How's
  
 It is or It's
  
 A: Who is she? 她是谁？
  
 B: That's Kim. 这是金。
  
 A: Where is she from? 她来自哪里?
  
 B: She's from Korea. 她是来自韩国。
  
 A: Does she live there? 她住在那里吗？
  
 B: Yes, she does. 是的,她是。She lives in Seoul.她住在首尔。
  
 A: Hi, my name is Dan. 嗨，我叫丹。 I'm
  
 from the US. 我来自美国。Where are you from?你来自哪里?
  
 B: Hi, my name is Tina. 嗨 我的名字是蒂娜I'm
  
 from China.我来自中国。
  
 A: Where do you live? 你住在哪里?
  
 B: I live in Beijing. 我住在北京。How
  
 about you?你呢?
  
 A: I live in San Francisco. 我住在旧金山。
  
    
  
    
  
    
  
  L1-U1-P4-5 :  Numbers 60-100 
  
 60 (sixty)   68 (sixty-eight)  70 (seventy)  74 (seventy-four)
  
 80 (eighty)   9 (eighty-nine)  90 (ninety)  93 (ninety-three)
  
 100 (one hundred)
  
  L1-U1-P4-6:  Letters R-Z 
  
 Rr: right正确的/右边  red红色的   Russia俄罗斯   read读   a ruler一把尺子 
  
 Ss: the Sun太阳  sad悲伤的   south南   Sydney悉尼   six六
  
 Tt: a taxi一辆出租车   a tomato一个番茄    toes脚趾   a teacher老师   ten十
  
 Uu: under下  unhappy不开心  an umbrella一把雨伞  uniforms制服
  
 the United States美国
  
 Vv: vegetables蔬菜    a violin一把小提琴  Vietnam越南   volleyball排球  
  
 Venice威尼斯
  
 Ww: water水  a woman女人  a watch手表  a window窗口  west西
  
 Xx: a box一个盒子  exit出口   anX-ray X光片   a fox一只狐狸   toxic有毒
  
 Yy: yellow黄色的  a year一年  yesterday昨天  yes是的   toy玩具
  
 Zz: zero零  a zoo动物园  a zipper拉链  jazz爵士乐   zebra斑马

4. 英语流利说 Level5 Unit2 Part3 Regulation in Company

Regulation    n.章程; 规章制度; 规则; 法规; (运用规则条例的) 管理，控制;
  
 To  sue , to take someone to  court  in a  legal  disagreement.
  
 They broke our contract and didn't pay, so we sued them and won.
  
 She sued her employer for firing her, but she lost because they had the right to fire her.
  
 We couldn't agree to her plan to avoid paying taxes,which was illegal, so she threatened to sue us.
  
  sue   v.控告; 提起诉讼; (尤指在法庭上) 提出请求;
  
  cord    n.法院; 法庭; 审判庭; 全体出庭人员; (尤指) 全体审判人员; (网球等的) 球场;
  
  legal   adj.与法律有关的; 法律的; 法律允许的; 合法的; 法律要求的;
  
 (When she left her job she sued her employer for not keeping its promise to pay her a bonus.)
  
 (We had to be very careful when we talked to her because we didn't want to be sued.)
  
 To  restrict , to put limit s  on something.
  
 This is a  restricted  area, so stay away.
  
 We need to restrict them from talking to anyone about our project.
  
 (The government tried to restrict people from going there because it was too dangerous, but some people insisted on going.)
  
 (We have  unlimited  access to their research and there are no  restrictions   on how  we use the information.)
  
 (We can't trust him, so we will have to restrict his activities until we know him better.)
  
 (If something is  confidential , you should restrict access to it.) 你应当限制对他的访问
  
  restrict    v.限制，限定(数量、范围等); 束缚; 妨碍; 阻碍; (以法规) 限制;
  
  restricted    adj.(大小或数量) 有限的，很小的; (指能做的事) 有限的，受限制的; 受(法规)制约的; 受控制的; 受约束的;
  
  stay away   [词典]远离; 不靠近;
  
  unlimited   adj.尽量多的; 任意多的; 无限制的;
  
  restriction   n.限制规定; 限制法规; 限制; 约束; 制约因素;
  
  confidential   adj.机密的; 保密的; 秘密的; 隐密的; 受信任的; 委以机密的;
  
 To  negotiate , to deal with  or   bargain  with others to reach an  agreement .
  
 Instead of starting a war, we should negotiate and find a way to  compromise .
  
 We are trying to negotiate  a better deal,  but it isn't easy.
  
 (If we  agree to  buy more, then we can negotiate for a  volume  discount.)
  
 (The price is too high, but if we negotiate we may be able to get a discount.)
  
  negotiate    v.谈判; 磋商; 协商; 商定; 达成(协议); 通过，越过(险要路段);
  
  deal with   [词典]处理; 应付; 与…打交道; 
  
  bargain   v.(与某人就某事) 讨价还价，商讨条件;
  
  agreement   n.协定; 协议; 契约; (意见或看法) 一致; 应允; 同意;
  
  compromise   n.妥协; 折中; 互让; 和解; 妥协(或折中)方案; 达成妥协(或和解);
  
  volume discount    n.数量折扣，总购量折让;
  
  Responsible for  or  responsible to,  to be responsible for something means to have the job of getting it done or taking care of.
  
 If you are responsible to someone, it means that you are working under their control.
  
 (He is responsible to the CEO, so he can't sign the contract without her final  approval .)
  
  Responsible for    [词典]为…负责; 是造成…的原因; 
  
  responsible to sb      对某人负责，表示前者服从于后者
  
  approval  n.赞成; 同意; 批准，通过，认可(计划、要求等); (商品) 试用，包退包换;
  
  Oversee  or  supervise , to control  or  direct a process or  project.
  
 One of his responsibilities was to supervise the rescue operations and keep things under control.
  
 As product manager, she oversees the work of several departments.
  
 (Their new project is  behind schedule  because nobody  oversees  how the departments  work  together.)
  
 (When we got to the accident, everyone was confused because  there was nobody there  to supervise.)      没有人在那
  
  Oversee     v.监督; 监视;
  
  supervise     v.监督; 管理; 指导; 主管;
  
  behind schedule    [词典]落后于预定时间;
  
 to control a direct process or project    to supervise
  
 Instead of starting a war,it's better    to negotiate 
  
 If you have a legal disagreement,you?     may have to sue
  
 Instead of starting a war, it's better?   to negotiate
  
 To be responsible for something means?   to have the job of getting it done or taking care of 
  
 If something is  confidential , you should  restrict access  to it.
  
 We had to be very careful when we talk to her because we didn't want to be sued.
  
 We have many responsibilities, but she is the one  responsible for product development.
  
 We need to report this to our boss because we are responsible to her and because she will judge our performance.
  
  lose   v.遗失; 丢失; (因事故、年老、死亡等) 损失，丧失，失去; 被…夺去;
  
  compromise  n.妥协; 折中; 互让; 和解; 妥协(或折中)方案; 达成妥协(或和解);                                v.(为达成协议而) 妥协，折中，让步; 违背(原则); 达不到(标准); (尤指因行为不很明智) 使陷入危险，使受到怀疑;

5. 英语流利说 Level5 Unit1 Part2 Reactions to News

Some people can remain clam even when everyone else is confused and upset.
  
 When you are clam you can think clearly and make good decisions.
  
 (Some people are easily upset and have a hard time controlling their emotions.)
  
 (Sometimes it's best to control your emotions and be calm rather than react in  anger )
  
  reaction  n.反应; 回应      confusedadj.糊涂的; 迷惑的   clearly adv.清楚地; 清晰地;  
  
  anger   n.怒; 怒火; 怒气;       in anger 气冲冲地，愤怒地;
   
  
 People react to disappointing news in different ways.
  
 Sometimes they get discouraged and lose their confidence.
  
 Sometimes they get depressed and begin to cry or even get drunk.
  
 (When disappointed, be calm, think clearly and act constructively)
  
 (when disappointed,it's much better to face the facts and decide what to do next than get discouraged)
  
  discouraged v.阻拦; 阻止; 劝阻; 使灰心; 使泄气; 使丧失信心;      
  
  get discouraged    网络灰心; 气馁; 送阑珊; 
  
  drunk  adj. 醉的； 陶醉的； 沉醉      get drunk喝醉了 
  
  disappointing 表示“令人失望的”的意思，一般用于事物给人的感觉。
   
  
  disappointed 表示“失望的”、“感到失望的”的含义，一般用以说明“人”自己的感觉。 
  
 People are  furious  when they are extremely angry.
  
 People who are furious at each other may  end up  fighting or trying to hurt each other.
  
 (Some people become furious when they are driving and another driver  cuts  in front of them) 插队 
  
 (When people are furious at each other they often yell and  insult  each other)
  
  furious  adj.狂怒的; 暴怒的; 激烈的; 猛烈的; 高速的; 盛怒的; 
  
  extremely  adv.极其; 极端; 非常;
   
  
  end up doing 最终以。。。告终 
  
  insult v.辱骂; 侮辱; 冒犯;
   
  
 To be excited is usually a good thing.
  
 People can become excited  while  watching a soccer match and seeing their team  score   a goal. 
  
 The opposite of exciting is  dull  or boring.
  
 (Everyone was excited when they heard that their favorite team had won the game.)
  
  When是at or during the time that 既指时间点也可指一段时间 
  
  While是during the time that    只指一段时间 
  
  score  v.(在游戏或比赛中) 得分 
  
  dull    adj.枯燥无味的; 无聊的; 令人生厌的; 不明亮的; 不鲜明的;
   
  
 Someone is  terrified  if they are extremely afraid and shaking with fear.
  
 Terrified people will often scream and run away form whatever is  threatening  them.
  
 (He was terrified when he thought e building he was in was going to collapse in the earthquake.)
  
 (Being in the earthquake was a terrifying experience,especially for the children.)
  
  terrified adj.恐惧; 很害怕;          shaking with fear    害怕得发抖
   
  
  threaten  .扬言要; 威胁; 恐吓; 
   
  
 (What can cause people to lose their confidence?)
  
 (What state of mind can help you think clearly and make good decisions?)
  
 (How do you feel if you get a discouraging new?)
  
 (What is the opposite of to be upset or excited?)   to be clam
  
 (What is the opposite of boring?)  exciting
  
 (People who can't control their emotions are difficult to work with.Their actions can upset everyone around them)
  
 some people are easily upset and have a hard time controlling their emotions.

6. 英语流利说 Level3 Unit3 Part1 - Dating Anniversary

Do you know what day it is today?你知道今天是星期几吗?
  
 What do you mean? 你什么意思?
  
 Is it a special day?今天是个特殊的日子吗?
  
 Oh, so you don’t remember.哦，所以你不记得了。
  
 Remember what? 记住什么?
  
 What’s so special?有什么特别吗?
  
 It’s our anniversary. 这是我们的周年纪念日。
  
 We started dating a year ago today.我们一年前的今天开始约会。
  
 Oh, really? Sorry.哦,真的吗?对不起。
  
 Just a minute. 只是一分钟。
  
 What do you think this is?你觉得这是什么?
  
 Oh, it’s a necklace.哦，是项链。
  
 Do you like it?你喜欢吗?
  
 Yes, I do. 是的,我喜欢。
  
 It’s lovely, especially the red heart. 它很可爱，尤其是红色的心。
  
 May I put it on? 我可以戴上吗?
  
 No, let me do it.不，让我来。
  
 So you did remember.所以你记得。
  
 Of course I remembered. 我当然记得。
  
 It’s a very special day for both of us. 这对我们俩来说都是非常特别的一天。
  
 I have something for you too.我也有东西要给你。
  
 You do?你会怎么做?
  
 Yes, but it will have to wait until later.是的，但是要等到晚些时候。
  
 Oh, I can’t wait. 哦，我等不及了。
  
 Tell me what it is.告诉我那是什么。
  
  (It's the first year anniversary of their first date.) (这是他们第一次约会的一周年纪念日。)
  
 Can you guess what it is?你能猜到是什么吗?
  
 Could you give me ahint?你能给我一个提示吗?
  
 We went there six month ago.我们六个月前去的那里。
  
 Oh, you mean Alfredo’s.你是说阿尔弗雷多。
  
 Yes, are you excited? 是的，你兴奋吗?
  
 You said you really liked the food there.你说你很喜欢那里的食物。
  
 Yes, that’s true. 是的,这是真的。
  
 I also remember the dessert, do you?我也记得甜点，你呢?
  
 Yes, but let’s not talk about that now. 是的，但是我们现在不谈这个。
  
 Let’s not ruin the surprise. 别毁了这次惊喜。

7. 英语流利说 Level6 Unit2 Part4 Listening - Aging Population

Aging Population 
  
  The world’s population is growing at a rate of a little more than 1% per year. 
  
 However, not all segments of the population are growing at the same rate.
  
 This graph shows that the rates of growth have 3 different groups, children, adults and the elderly.
  
 As you can see, while the population of children is fairly constant, the elderly population is increasing at the fastest rate.
  
 This is due to very low birth rates in developed country and birthrate declines in most developing countries.
  
 As a result of these trends, the world’s population is aging.
  
   Different segments of the population are growing at different rates.  
  
 Between 2015 and 2050, the percentage of world’s population over 60 is expected to nearly double.
  
 In 2015 there were 900 million people over 60; in 2050 the number should be around 2 billion.
  
 Aging populations are becoming a huge problem in many countries, especially developing counties.
  
 It used to be that many elderly people lived with their family and helped take care of the next generation.
  
 They had a place to stay and people to help take care of them when they needed assistance.
  
 Now however, many elderly people, or senior citizens, are left on their own.
  
 This is partly the result of people having fewer children, and also because of the massive urbanization.
  
 Young and middle-aged audits have left the rural area for economic opportunities only available in large urban centers.
  
 As a result, there is no one to care for the elderly who are left behind to live on their own.
  
 This is especially true in developing countries.
  
  Fewer elderly people are being cared for by their families.  
  
 With an aging population, health problems become a growing concern.
  
 Some of the leading conditions that accompany aging include vision problems, hearing loss, diabetes and dementias such as Alzheimer's disease.
  
 These problems can lead to disabilities that make it difficult to live without assistance.
  
 With diseases such as Alzheimer's, people lose their memory and are unable to recognize their own children.
  
 Worldwide, more than 46% of people aged 60 and over have disabilities.
  
 Getting meals and medical care, for example, becomes both expensive and difficult.
  
 As a result, the cost of providing services to the sick and disabled can become a huge problem.
  
  Massive urbanization means people moving from rural to urban areas. 
  
  Massive urbanization occurs when many people move from rural areas to large urban centers. 
  
  A disabled person is someone who generally needs some kind of living assistance. 
  
  Elderly people are often referred to as senior citizens. 
  
   Memory loss is one example of a disability.  
  
   With an aging population there will be more sick and disabled people to care for.

8. 英语流利说 Level6 Unit2 Part2 Listening - Talking about Modals

Talking about Modals 
  
 Now that you'restudying English at a high level, let's get a better understanding of   modals.
  
 By now you should already have a good understanding of what they mean.
  
 Here are the modals which are used to express degrees of certainty.
  
 will/shall/may/can
  
 These modals are  used  for making  predictions , judgements and speculations.
  
 They  indicate  how much a speaker knows about the  likelihood  of an  event. 
  
 First, the modal "will" expresses certainty, as in " If you heat water, it will boil." 
  
 Based on what is known, the speaker is CERTAIN it will happen.
  
 The modal "may" expresses possibility, as in "It may rain this evening, but I'm not sure."
  
 Based on what is known, the speaker  asserts  that the event is possible rather than certain or impossible.
  
 The modal "can" expresses potentiality, or ability, as in "He can afford it, but he may decide not to buy."
  
  Sam can’t run faster  than I can.
  
   The modal “will” shows that the speaker is making a prediction with certainty.  
  
   The modal “may” shows that the speaker thinks something is possible.  
  
 The modal"shall" is a bit different from the others.
  
  "Tina shall be there" means the speaker is determined that Tina will be there .( We shall overcome all obstacles! )
  
 In other words, the speaker is determined to get her to come and will try to influence events to make it happen.
  
 We would never say: "It shall rain."
  
  Nobody can make it rain, so whether or not it rains is beyond anyone's control. 
  
 If someone  were  to say that, it  would  seem as if they were  claiming  the power to control or  influence  nature.
  
 Note that the question "Shall I open the door?"   invites the person who is asked to make the decision.
  
 Whether or not the door is opened depends on the person's answer.
  
 In contrast, "Will I open the door?" asks for a prediction rather than a decision. （  Will she be at the party?  ） 
  
   She has something else planned for that evening, so she can’t come to the party.  
  
 Note that these modals can be weakened or removed from reality by the use of their past tense form.
  
  would/should/might/could 
  
 "We would go if we had more money, but we don't."
  
 This sentence expresses the speaker's certainty of going IF they had more money, which they don't.
  
 So the certain prediction exists, but in an imaginary or unreal situation.
  
  The modal "might" expresses less possibility than "may", so "might go" is less likely than "may go". 
  
  The modal "could" expresses less potential than "can", and is often used in conditionals. 
  
 "If he could come" expresses less potential than "If he can come".
  
 The sentence,"If he could come, we would all be happier" expresses the feeling that in fact, he can't come.
  
   It isn’t certain, but there’s a good probability that they will finish at five.(They might finish at 5:00.)  
  
   We don’t know for sure, but there is still a probability that they can leave on Friday.(They may not be able to leave on Friday.)  
  
 Here is the second set of modals.
  
 These modals express degrees of logical force or social expectation.
  
  must/ had better/should/ ought to 
  
 Note that none of them has a past tense or weakened form.
  
 The first one,"must indicates logical or social necessity.
  
 It expresses the strongest logical or social force.
  
 The modals "should" and "ought to" assert that something is probable or expected, but not necessary.
  
 The modal "had better" expresses advisability.
  
 In other words, if someone "had better" do something, they should do it or there may be negative consequences.
  
 Therefore, "had better" has the feeling of a threat, as in "You had better be there."
  
 This isn't the same as "You should do it," which means you are expected to do it,but without an implied threat if you don't.
  
   The modal “must” expresses logical or social necessity.  
  
  One interesting rule is that no more than one modal can be used with any verb. 
  
 There are no  exceptions  to this rule.
  
 Therefore, it's incorrect to say: "He will must be there."
  
 To avoid  breaking  this rule, there are other words that have the same meaning, but are not  modals. 
  
 In the case of "must", for example, we use "have to"  as  in "He will have to be there."
  
 Similarly, we cannot say "He may can come."
  
  Instead , we say "He may be able to come."
  
 One last thing to note about modals.
  
 They use the same form regardless of what the subject is.
  
 If the grammatical subject is l, it, we or they, we use the same form, will.
  
 We would never say "He wills be there."
  
 But with non-modal forms, such as "have to" we must change the form to match the subject.
  
 "He has to be there" and "I have to be there".
  
   “What must we do?” has the same meaning as “what do we have to do?”  
  
   Tom must be taller than Sue because he’s taller than Ben and Ben is taller than Sue.  
  
   The expression “be able to” has the same meaning as “can”, but isn’t a modal.