第一篇：大學機械專業英語情景對話

Mr.Liu:Come in ,please.劉先生：請進。

Mr.Bao:Good afternoon,Mr.Liu.包先生：.下午好，劉先生。

Mr.Liu:Good afternoon.Have a seat,please.劉先生：下午好，請坐。

Mr.Bao:Thank you very much.包先生：非常感謝。

Mr.Liu:Are you Mr.Bao?

劉先生：您是包先生嗎？

Mr.Bao:Yes,I am.包先生：是的。

Mr.Liu:I have read your resume.I know you have worked for 3 years.Why did you choose to major in mechanical engineering?

劉先生：我看了你的簡歷，知道你已經工作過3年。為什么你選擇了機械工程專業呢？ Mr.Bao:Many factors lead me to majoring in mechanical engineering.The most important factor is I like tinkering with machines.包先生：許多因素致使我選擇了這個專業。最重要的一個因素就是我喜歡修理機器。Mr.Liu:What are you interested in about mechanical engineering?

劉先生：關于機械工程，你最感興趣的是什么？

Mr.Bao:I like designing products and one of my designs received an award.Moreover,I am familiar with CAD.包先生：我喜歡設計產品，我的一份設計作品還得過獎。而且，我非常熟悉CAD。Mr.Liu:Great.Then what is your technical post title now?

劉先生：很好。那么你現在的技術職稱是什么？

Mr.Bao:I’m a senior mechanical design engineer.包先生：.我現在是高級機械設計工程師。

MrLiu:Do you take the original certificate with you?

劉先生：你把證書原件帶來了嗎？

Mr.Bao:Yes.Here it is.包先生：.是的，給。

Mr.Liu:Why did you decide to apply for this position?

劉先生：為什么你決定申請這份崗位？

Mr.Bao:Your company has a very good reputation.I’m very interested in the field of your company.包先生：.貴公司聲望很高。我對這領域也很感興趣。

Mr.Liu:Well，thanks.I’ll let you know the result of the interview as soon as possible,Goodbye.劉先生：那好吧，謝謝你。我會盡快告訴你面試結果的，再見。

Mr.Bao:Thank you.I do hope the answer will be favorable.Goodbye.包先生：謝謝，我希望結果順利。再見。

第二篇：大學機械專業英語總結

Unit 11 Machine tools have evoled from the early foot-powered lathes of the Egyptians and John Wilkinson’s boring mill.Most machining operations produce parts of differing geometry.Flat or plain surfaces are frequently required.Multiple-edged tools can also be used.The basic operations performed on an engine lathe are illustrated in Fig11-3.Those operations performed on external surfaces with a single point cutting tool are called turning.The objective of boring a hole in a lathe is:

1.Toenlarge the hole 2,Tomachine the hole to the desired diameter.3.To accurately locate the position of the hole.4.To obtion a smoth surface finish in the hole.Unit12 Broaching is a process for internal or external machining of falt, round, or contoured surfaces.Sawing is the parting of material by using metal disks, blades, bands, or abrasive disks as the cutting tools, Reaming is a machining process for enlarging, smoothing and/or accurately sizing existing holes by means of multiedge flutes cutting tools.Unit 13 Welding is essential to the expansion and productivity of our industries.Electroplating is a process in which a metal is deposited onto a metallic substrate.Soldering is the joining of metals by causing a lower-melting-point metal to wet or alloy with the joint surfaces and then freeze in place.Cleaning operations are performed both preparatory to and after finishing operations.Unit 14 Lathes are designed to rotate the workpiece and feed the cutting tool in the direction necessary togenerate the required machined surface.Vertical-boring machine

horizontal-boring machine

planning machine

horizontal-milling machine

vertical-milling machine Unit 15 AJM removes material through the mechanical cation of a focused stream of abrasiveladen gas.USM is a mechanical material removal process which is used to generate holes and cavities in hard or brittle workpieces.ECM is a process that removes material through the ptinciple of eiectrolysis.Unit 16 Group technology is a very important methodology in today’s manufacturing environment, particularly for batch production, and is becoming increasingly significant.For parts to be grouped based on either design characteristics and featuers or manufacturing processes, they must be classified into predetermined categories and coded for retrieval and use.Unit 17 Flexibility is an important characteristic in the modern manufacturing setting.Cellular manufacturing is the concept of organizing plant facilities and process planning for family-of-part manufactuer.Machine centers originsted out of their capability to perform a variety of machining operations on a workpiece by changing their own cutting tools.Software is the vital invisible element than actually drives the FMS.There are two basic levels of software required for an FMS: 1:operating system 2:application software Unit 18 Computer integrated manufacturing is the term used to describe the modern approach to manufacturing.Management is the process of making directing the activities of personnel to achieve stated objectives.An AGV is a computer-controlled, driverless vehicle used for transporting materials form point in a manufacturing setting.In any discussion of AGVs, three key terms are frequently used: 1:Guide path.2:Routing.3:Traffic management.Unit 19 Part acquisition time is highly dependent on the nature of the layout of the assenmbly area and the method of assembly.Assembly in the manufacturing process consists of putting together all the component parts and sub-assemblies of a given product, fastening, performing inspections and functional tests, labeling, separating good assemblies from bad, and packaging and or preparing them for final use.Unit 20

Automation is a widely used term in manufacturing.Fixed automation is what Harder was referring to when he coined the word automation.Numerical control can be defined as a form of programmable automation in which the pross is controlled by numbers, letters, and symbols.The program of instructions is the detailed step-by-step set of directions which tell the machine tool what to do.The highest degree of automation obtainable with special-purpose, multifunction machines is achieved by using transfer machines.

第三篇：機械專業英語

機械專業英語楊亞炬 20100334506

機電103班

考慮磨削力的磁懸浮磨床電主軸轉子系統動態特性分析

摘要:以電磁軸承支承的磨床也主軸為研究對象，建立了轉子的彈性支承模型，對其進行了模態分析，得出轉子固有頻率隨支承剛度變化的規律;對施加磨削力時轉子的穩態響應特性進行了分析，根據危險界面的節點位移，初步確定了主軸系統的穩定性。

關鍵詞:電磁軸承支承系統;磨床電主軸;模態分析;穩態響應特性 引言

電磁軸承具有無摩擦、元磨損、高速度、高精度及可長期免維護等優點，因此被廣泛應用于高速旋轉類機械中。采用電磁軸承支承的磨床電主軸是典型的機電一體化系統，由于磨削過程的復雜性，其支承主軸系統的影響與其他軸承相比更為突出[1 刀。轉子的動態特性是電磁軸承支承特性與轉子結構動力學特性綜合作用的結果。在對轉子實施控制之前，研究轉子本身的動力學行為對控制系統的設計是很重要的時。本文以某電磁軸承支承的磨床電主軸為研究對象，建立了轉子的彈性支承模型，對其進行了模態分析和施加磨削力時的穩態響應特性分析。軸、砂輪連接桿、前后徑向軸頸套、前后平衡環、止推盤和隔磁環等組成，其他部件與轉軸之間采用過盈連接。

轉子總重5.90kg，總長507mm，穩定懸浮時轉子和徑向軸承之間的間隙為0.2mm，軸向軸承

1.砂輪2 傳感器3.前輔助軸承4.前徑向軸承5.轉軸6.軸向軸承7.冷卻水套

8.電機部分9.后徑向軸承10.后輔助軸承間隙為0.3mm。建立有限元模型

電磁軸承支承為典型的彈性支承，有限元分析模型采用16 個彈簧單元模擬徑向電磁軸承的16 個磁極。止推盤兩側分別采用8 個彈簧轉軸 根據轉子的結構形式，用ANSYS 建立起轉子的實體有限元分析模型，模態分析

支承剛度對轉子固有頻率的影晌根據轉子的有限元分析模型，用ANSYS 對其進行模態分析[5J。忽略彈簧單元的阻尼，支承剛度在5X106~lXI09N/m 范圍內變化階模態，得到轉子的正進動固有頻率和負進動固有頻率，進一步研究臨界轉速時，首先剔除負進動固有頻率[6J。可以得到轉軸前四階固有頻率隨剛度變化曲線,轉子的正進動固有頻率隨支承剛度的增大而增大，且轉子的低階固有頻率隨支承剛度增加的幅度較大。當支承剛度增大到1.6X10 8 N/m 時，轉子的2~4 階固有頻率已無多

模態分析完畢后，將磨削激振力施加于砂輪 處進行諧響應分析，在砂輪外圓節點7746 處施加Y 方向力(實部為88.328N、虛部為1.9737N)和Z 方向力(實部為1.9737N、虛部為88.328N)，這樣磨削力為一簡諧力。COMBIN14 單元的剛度取2.0X10 7 N/m，為分析轉子在高頻段的響應，將激振力的頻率范圍擴大至0~1600Hz，分20 個載荷步進行諧響應分析。

當主軸工作在30000r/ min(對應額定工作頻率500.0Hz)、48 OOOr/ min(對應最高工作頻率800.OHz)，即轉速處于一階與二階臨界轉速之間時，由轉子的二階振型(圖5)可以看出，轉子在砂輪、前保護軸承、前徑向軸承和后徑向軸承處的中心截面為危險截面。圖7~ 圖10 分別為砂輪、前保護軸承、前徑向軸承和后

徑向軸承處的振動幅值一頻率響應后徑向軸承處節點4484 振動幅值一頻率響應曲線移增大幅值在一階固有頻率處最小，二階固有頻率處最大，三階固有頻率處次之。

磨床電主軸的結構參數如下:轉子與前后保護軸承的間隙為O.lmm，與前后徑向軸承的間隙為0.2mm。由表3 可知，當激振力頻率達到轉子一階、三階固有頻率時，轉子產生的共振位移在轉曲線，在有限元模型上分別對應節點7746、7818、7559 和4484 的振動幅值頻率響應。各危險截面的節點Y 方向位移如表3 所示。當激振力頻率達到轉子的固有頻率時，轉子的位移(振動幅值)會突然增大，通過前三階的幅頻響應曲線可以看出，轉子位子間隙范圍之內;但達到轉子二階固有頻率時，轉子產生的共振位移會超出間隙要求，使得轉子與軸承碰撞，發生危險，因此應避免激振力頻率達到轉子的二階固有頻率。由轉子的二階振型可以看出，轉子在后保護軸承處的徑向位移小于后徑向軸承處的徑向位移，故可判定后保護軸承處在Y 方向的位移小于

2.0 X 10 一7 m。各危險截面的節點位移均在間隙范圍內，因此可初步判定轉子在額定轉速和最高

轉速下工作時，給其施加Fn = 88.328N、Ft =1.9737N 的磨削力，可穩定工作。結論

(1)完全彈性支承下，電主軸轉子固有頻率的總體變化趨勢隨支承剛度的增大而增大，并且在支承剛度較低時，固有頻率隨支承剛度的變化較大。當支承剛度到達一定值時，轉子的前四階固有頻率趨于穩定，在設計控制系統時可控制軸承的剛度高于此值，以便轉子具有穩定的臨界轉速。

(2)在施加了磨削激振力后，通過幅值頻率響應分析確定了幾個危險界面的節點位移，可初步判斷主軸系統的穩定性。

Dynamic Analysis for Electric Spindle Rotor System of Magnetic Levitation Grinder

Considering Grinding Force

Abstract: This paper bui1t an elastic bearing model for the rotor of grinder electric spindlesupported by electromagnet bearing and analyzed the mode of the rotor , educed the laws about therotor inherent frequencies changing along with bearing stiffness.Then, it analyzed steady stateresponse characteristics of the rotor while applying grinding force.According to the nodedisplacements of danger interface ,stability of spindle system is ensured initially.Key words: supporting system of electromagnet bearing;grinder electric spindle;mode analysis;steady state response characteristics.Introduction

Electromagnetic bearings with no friction, wear yuan, high-speed, high precision and long-term maintenance-free, etc., it is widely used in high-speed rotating machinery.The electromagnetic bearing grinder electric spindle is a typical mechatronic systems, due to the complexity of the grinding process, the supporting spindle system compared with other bearing more prominent [1 knife.The dynamic characteristics of the rotor the electromagnetic bearing characteristics and rotor structure dynamics combined result.Before control of the rotor embodiment, the study rotor dynamic behavior of the control system design is very important.An electromagnetic bearing grinder electric spindle rotor elastic support model, its modal analysis and steady-state response characteristics in the grinding force is applied.Shaft, wheel connecting rod, front and rear radial journal cover, front and rear stabilizer ring, thrust plate, and every other magnetic interference connection between the other components and the shaft.The rotor total weight of 5.90kg, Total length 507mm, stable suspension of the rotor and the radial bearing gap of 0.2mm, and the axial bearingwheel sensor 3.Former auxiliary bearing front radial bearing 5.Shaft axial bearing cooling water jacket motor section 9 after radial bearing 10 after the auxiliary bearing clearance of 0.3 mm.Finite element model

The electromagnetic bearing the typical elastic support, finite element analysis model with 16 spring element to simulate the radial magnetic bearing 16 pole.On both sides of the thrust plate 8 spring pivot

Established with ANSYS based on the structure of the rotor, the rotor solid finite element analysis model, Modal Analysis Support stiffness IMPACT natural frequency

of the rotor based on the finite element analysis model of the rotor, modal analysis using ANSYS its [5J.The damping of the spring element is ignored, the the support stiffness 5X106 ~ lXI09N / m range order modal rotor is precession natural frequencies and negative precession natural frequency, further study of the critical speed, the first natural frequency [excluding the negative precession 6J.Can get the shaft first four natural frequency of the curve with the change in stiffness of the rotor is precession natural frequency with the support stiffness increases, and the rate of increase of the low-order natural frequency of the rotor with the bearing stiffness.The 2-4 order natural frequency of the rotor Found when the supporting stiffness increases to 1.6X10 8 N / m,Modal analysis after grinding exciting force is applied at the wheel at the harmonic response analysis, the Y direction of the force applied to the wheel outer node 7746(88 328N real part, imaginary part 1 9737N), and Z directions force(the real part of 9737N, the imaginary part of the 88 328N), so that the grinding force of a simple harmonic force.COMBIN14 element stiffness take 2.0x10 7 N / m for the analysis of the response of the rotor at high frequencies, the frequency range of the excitationforce is expanded to 0 to 1600Hz, 20 load step harmonic response analysis.Spindle 30000r / min(corresponding to the nominal operating frequency 500.0Hz), of 48 OOOr / min(corresponding to the maximum operating frequency of 800 OHZ)that speed in the first-order and second-order critical speed, the second rotor vibration type(Figure 5)can be seen, the rotor wheel, the front protective bearings, the radial bearing and the rear radial bearing at the center of a sectional view of the dangerous section.Figures 7 to 10 respectively for the wheel, the front protective bearings, the front radial bearing and a radial bearing at a frequency response of the vibration amplitude of the vibration amplitude of the radial bearing at the node 4484 frequency response curve shift increased amplitude in a The natural frequencies at the minimum, followed by the natural frequency of the second-order, third-order natural frequency.Of Grinder Spindle structure parameters are as follows: rotor protection before and after bearing clearance O.lmm the front and rear radial bearing clearance of 0.2 mm.Seen from Table 3, when the frequency of the excitation force to the rotor-order, third-order natural frequency, the resonance generated by the rotor displacement in the transfer curve in the finite element model, respectively corresponding to the nodes 7746, 7818, 7559 and 4484, the amplitude of vibration frequency response.The nodes in the Y direction of the dangerous section of the displacement shown in Table 3.When the frequency of the excitation force is reached when the natural frequency of the rotor, the rotor displacement(vibration amplitude)will suddenly increases, frequency response curve of the web through the first three can be seen, within the scope of the clearance of the rotor charts;but reached rotor Second Order natural frequency of the rotor of the resonance displacement will exceed the spacing requirements, so that the rotor and the bearing collision danger, the second natural frequency of the exciting force the frequency of the rotor should therefore be avoided.By the second-order vibration of the rotor can be seen, the radial displacement of the rotor after protection of the radial displacement of the bearing

is less than the radial bearing at the displacement of the bearings in the Y direction, it can be determined after protection Smaller

2.0 X 10 a m.Of the dangerous section of the nodal displacements gap preliminary determination rotor at rated speed and maximum

Speed work when applied to its Fn = 88.328N FT = 9737N grinding force can work stably.Conclusions

(1)fully resilient support, the overall trend of the natural frequency of the electro-spindle rotor with bearing stiffness increases, and the supporting rigidity is low, the larger the change of the natural frequency with the support stiffness.When the supporting rigidity reaches a certain value, the first four natural frequencies of the rotor is stabilized in the design of the control system can control the stiffness of the bearing is higher than this value, the stability of the critical speed for the rotor having.(2)In the grinding exciting force is applied by the amplitude frequency response analysis identified several risk interface nodal displacements can determine the initial stability of the spindle system.

第四篇：大學英語口語情景對話

自我介紹

My name is ________.I’m 20 years old.My major is ______________.In my spare time, I like to read novels.Sometimes I surf the Internet and download the E-books to read.In addition to reading, I also like watch English movies from which I learned a lot of daily life English and saw a lot of different things.Watching English movies and listen English songs also enlarges my vocabulary words and improve my pronunciation.My maxim is: To live is to learn;to learn is to better live.2.Exchange information with your partner on your favorite sports, teams and players.A：Hi, Hu.How are things with you?

B: I’m just taking one day at a time.A: How come you look so tired?

B: Because I stayed up to watch Football game on air these nights.A: Football game? You really had strong football aspirations!

B: yeah!I ’m so exciting to talk about football.I like Messi for a long time ,and I also like Barcelona Team

A: Recently.The Barcelona Team has aroused much public concern around us.Are there any good words about the team?

B: Of course!The Barcelona Team won the European Champion and their performance was as good as we might except.A: What about Messi ,the person who catches people’s eyes in any situation?

B: Yes, He did well, and he made the second goal.That was a great goal!Which player do you like?

A: I prefer basketball than football, my favorite player is Kobe, who comes from L.A Lakers.B: I heard that the team didn’t do well in the NBA playoff.A: It’s sad to say that , though they have won 16 times of champion, they still stuck on Quarterfinal.B:What a pity.What about Kobe’s performance in the NBA match?

A: Kobe is a brilliant and energetic player.He made every effort to save the situation, but it’s all in vain

B: Don’t be sad ,I believe they will rise from the ashes oneday.A: I believe too, it’s really enjoying our talk.However I really have to go now

B: Well, it’s too bad that you have to go.A: Perhaps we can get together another time

B: Ok, bye!

A: Bye!

5.Exchange information with a classmate on your favorite pop star.A: Hey liu, good morning.B: Hey hu good morning!How about your weekend?

A: It’s wonderful!I attend Madonna’s concert.B: Really? I watched the advertisement on TV few weeks ago.How do you like the concert? A: I thought it was great!Madonna is my favorite pop star, her costumes ['k?stju:m 服裝] are so unique and she performs with so much energy.B: What about her songs?

A: They’re so upbeat and easy to dance to, but I can’t understand what she sings.B: That’s funny, neither can I.A: So who is your favorite star?

B: my favorite pop star is wanglihong.you can call him leehom.A: I appreciate him too, he is very brilliant.B:Yeah, Wang grew up in the United States.Blessed with a mix of brains and talent, he spent his youth performing in local musicals, then pursued a degree in music at Williams College, followed by a masters degree from the prestigious Berkley School of MusicA: You know much about him.B: In addition to writing and producing his own music, Wang has also dabbled in movie projects around Asia.A: That’s cool.Did you see his concert ever?

B:No , how I wish I can attend his concert.A: Wish your dream would come ture!

B:Thaks, oh it’s time for class!See you after school.A: See you!

6.Exchange ideas with your partner about a course or teacher you like best in college

7.Exchange ideas with your partner about ways to make college life more rewarding

A: How are things with you?

B: I’m just taking one day at a time。

A: How come you look so tired?

B: Because my roommate stayed out to play computer games, I can’t sleep with that noise.A: That’s a common sense.At college a growing number of students, apparently don’t know the way which makes our college life more rewarding.B: That’s sounds reasonable.That’s why many students addict themselves to

computer games.And what’s your opinion about making college life more rewarding? A: From my viewpoint, we are supposed to make a plan to broaden our horizons and explore our intelligence.So that we can enrich ourselves and have a substantial life.B: Make a plan? That’s a good idea.Can you explain the precise details about what we can plan?

A: About daily study, we can make a clear plan and then achieve this goal step by step.Outside school, we can do some volunteer works to rich our college life.Meanwhile the university campus has excellent exercise and recreation facilities, we can make full use of them.What’s your opinion?

B: In my opinion, there are many way from which we can obtain much information and knowledge.For example, we can watch some classic movies, so that we are able to practice our pronunciation.Also we can listen some music to relax ourselves.A: I agree.Oh, it’s late ,I really enjoy our talk, but I need to go now.B: It’s too sad that you have to go, hope we can get together next time.A: Ok, bye!

B: Bye!

9.Exchange ideas with your partner about what kind of life your want in the future.A: Hi, hu.What are you doing here?

B: Hi liu, I am looking for some books about English.A: English? I never know that you have such a strong passion for English.B: I have an examination of college English test band six, so I need to work hard.A: I see, so are you going to take a postgraduate exam in the future?

B: Yes, I want to take up __________after graduate.But I was wondering whether I can make it.This has been a hard course for me.A: Come on, this is just what you are cut out for!You always at the top of our class, you’re pretty good, trust yourself!

B: That’s very nice for you to say so.What about you? Work? Study abroad or test the graduate student?

A: Maybe I’ll choose to work.B: That’s great, but why don’t you choose to be a postgraduate?

A: Because I don’t think I have a English studying brain, but you know that, English is the major course in the postgraduate examination.I can’t handle it.B: You’re right!English has been a puzzle for many students.However, choose to work will be a good choice.So what kind of work will you engaged in?

A: I want set up a computer company by myself, do my own business.B: That’s cool!I can’t wait to visit your company.A: I’ll inform you once I start business.B: That’s a deal, oh, it’s late, and my girlfriend is waiting for me.I need to go now.A: Ok, see you next time,B: see you!

第五篇：秘書工作情景對話

2.接聽電話

秘書：您好！這里興和文化傳媒有限公司人事部辦公室，請問您貴姓？

客戶：我是某某的經理，怎么現在才接電話，是不是不想談合同的事啦？（語氣非常苛刻）

秘書：對不起，讓您久等了，剛才公司處理的正是這件事。客戶：哦，這樣啊。

秘書：實在不好意思！非常抱歉！請問還有什么可以為您服務的嗎？

客戶：那麻煩你轉告張經理，今天下午三點某某某見。秘書：今天下午某某某地，好！我一定及時轉達。客戶：再見！秘書：再見 3.簽收信件

快遞員：您好，請問你們經理在嗎？有他的信件需要他來簽收。

秘書：我們經理現在有事出去了現在不在，我是他的秘書，我來幫他簽收吧。快遞員：好的，請在這里簽上你的名字。。

秘書：好了，簽好了，辛苦你了！4.日程安排

經理： 高葉，昨天開會的內容整理出來，發給我看一下。

高葉： 王總，昨天的會議內容我已經發到你的E-mail上了

經理： 嗯，辦事效率大大提高啊！值得夸獎 高葉： 這是我應該做的。

經理： 好，你明天去幫我定兩張下個星期去北京的飛機票，具體時間你根據我的行程安排吧！

高葉： 好的，你下周一至周三沒有行程安排 經理： 行，就這幾天吧！

高葉： 好的！5.突發事件處理

經理正在辦公室工作，突然斷電，打電話給秘書詢問： 經理：高葉，怎么回事，怎么突然斷電了。

秘書：哦，不好意思經理，我馬上打電話給后勤工作人員打電話。。

秘書：喂，你好，是后勤工作人員嗎？請問現在怎么突然停電了？ 工作人員：哦，是這樣的，由于維修工作的需要暫時停電幾分鐘。秘書：嗯，好的，你們抓緊時間維修吧，經理那邊還有客人在。工作人員：嗯，我們會抓緊時間的。

接待來賓

今天有位重要客人來訪。秘書要在辦公室外迎接客人并進行自我介紹，然后引導他們上樓，進入經理辦公室。演示整個過程。

B：你好，我是經理的秘書，我叫高葉。A：你好。

B：歡迎來到本公司，你們一路上辛苦了。A：不會不會。

B：經理現在在樓上處理一些急事，不能親自下來迎接，所以派我下來迎接，他為不能親自迎接您感到萬分抱歉。

A：不礙事的，有急事當然是要先處理急事的。B：吳女士，謝謝您的體諒，那請您這邊請。A：好的。

7.人事溝通協調

高葉：王潤，今天下午公司有個重要會議要開，你去通知一下胡穎讓她早點過來做下會議準備。

王潤：嗯，好的，那會議具體時間是？ 高葉：下午三點，在會議廳，麻煩你了。王潤：沒關系的，還有其他事嗎？

高葉：沒有了。就這樣，那下午見，拜拜！王潤：拜拜！