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標(biāo)題: 從業(yè)超過50年的以色列機(jī)械工程師：在工程計算上，別信學(xué)校那套,！ [打印本頁]
作者: 小師妹_c937B 時間: 2016-9-26 13:56
標(biāo)題: 從業(yè)超過50年的以色列機(jī)械工程師：在工程計算上，別信學(xué)校那套,！
標(biāo)題黨了一把,，其實(shí)這是個機(jī)械英語教學(xué)帖，當(dāng)然，里面干貨也不少。
今天這篇文章的主題是 engineering calculation,。是一個資深以色列工程師對于剛?cè)胄械哪贻p人在工程計算上的意見和建議,。
老規(guī)矩,，我先把原文貼出來，大家自由翻譯文章,，并把譯文貼在回復(fù)中,，可以是文章中的一句，一段,，有空的同學(xué)翻譯全文也是極好的,，參與學(xué)習(xí)的社友都能得到威望獎勵。
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以下是作者簡介,。作者出生在以色列,，畢業(yè)于以色列理工學(xué)院（傳說中的中東MIT）機(jī)械工程專業(yè)，專注于機(jī)械設(shè)計超過50年,，目前在以色列本古里安大學(xué)教授機(jī)械光學(xué)設(shè)計,。
Adam Rubinstein
Born in Israel, studied Mechanical engineering in the Technion, specialized in mechanical design and particularly mechano-optics. Over 50 years experience as a design engineer, and about 24 of them as an independent consultant. lately, partially retired and teaching mechano-optical design at BGU in Beer-Sheva, Israel.
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; x, t# M; y' D! u- j0 k下面是正文分隔線
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$ I/ z. z; F. `# V1、Don't believe everything they teach you at school, real life is very different!
2,、You should immediately dismiss from your head the idea that there is only one right answer to any design question. Keep your mind open to all options.
3,、Design failures can have many different forms and all should be considered.
4、What came first, the chicken or the egg? The analysis of a hypothetical design will always start with a range of assumptions which can be adjusted.
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The difference between school and “real life” problem solving
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When we pass from high school to university we bring with us the idea that answers are obtained by engineering calculations. We use analytical formulas and we are educated to believe that the results are either right or wrong – there is no in between and no grey areas. We are used to having all of the relevant data associated with a problem. I even remember checking my answers by verifying that if I used all the data given in a problem – do we always need to use all of the data to get the answer?
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This is not real life. Data is never “given”, it is usually incomplete, and there is not necessarily a single “right” formula. I have seen many students ask me which of two different formulas (teeth strength and surface fatigue) to use for calculating gear wheels. It was very difficult to make them understand that both were “right” and that they should use the worst case. Always err on the side of caution.
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There are many ways to fail (but it only takes one)
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While teaching strength of bolts I once calculated a bolt for a number of different possible failure modes. I calculated for the “standard”, the pull strength of the core for the less common shaving of the threads and also for shearing of the head and a few more bizarre possible modes. I showed that, although all are possible, the standard bolts will nearly always fail at the core first. However, under certain conditions (too few mating threads, a weak mating material, etc) the threads might shave first. Confused? Let me explain….
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Forgetting the other possible failure modes may be very dangerous. As the designers of the first British jet airliner, the Comet, discovered at the high cost of lost planes and lives in the early 1950’s.
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The risks of designing for the real world
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It is always risky to design something new. High flying jets and the use of aluminium were pretty new in those days. British engineers also failed to realise the effects of repeating decompression loads and stress concentrations on the fatigue strength of the aluminium airframe. Calculating for static loads was just not enough.
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How did they calculate their airframe then? Computers were still in their infancy and FEA programs were not written yet. They had to use stress formulas and manual structural analysis tools. Even today, with our powerful computers and programs, it is not easy to analyse a structure as complex as an airframe. We have better research tools but the old problems and challenges are still there.
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Skill, common sense and patience
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What they must have done was to make simplifications, calculating parts of the structure one at a time and performing tests for real parts and assemblies. This was in fact a combination of some calculations with experimental testing to prove the design. We must admit that in spite of the crude tools they had they did a good job after all.
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We would like to think that today we do much better in our design work. Indeed our tools are far better than theirs but in principle what we do is very much the same. We build our models and test them by applying FEA programs. The fact that we can run the test on a computer model rather than on a hardware model is only a difference of time and cost. We must still have a finished design before we can test or analyse it.
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What came first, the chicken or the egg?
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It is a vicious circle: we need a complete design in order to test it, yet we cannot complete the design without calculating it. How do we break this vicious circle? By guessing our way to the design! By experience, by rules of the thumb and by rough calculations based on preliminary design ideas and sketches!
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Don’t forget that these early assumptions can be revisited and recalculated but at least they allow us to begin the process.
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作者: www.zdscj.com 時間: 2016-9-26 14:10
抱歉,，看不懂里面的內(nèi)容啊~~我回去好好學(xué)學(xué)英文
作者: 青wings 時間: 2016-9-26 14:19
1.不要全部相信你在學(xué)校學(xué)到的東西,，現(xiàn)實(shí)生活是完全不同的2 Q% V @1 N$ [9 z$ I0 h
2.你應(yīng)該完全的摒棄大腦里對于一個設(shè)計只有一種正確方案這樣的想法，保持你的思路找到所有的方案
, R+ n) Y5 j! n" V3 b- O8 [! x# L3.設(shè)計的不當(dāng)之處會表現(xiàn)在許多方面,，每個方面都應(yīng)被考慮/ B8 \" {! m5 X. @& a- [; T
4.先有雞還是先有蛋,，許多創(chuàng)新設(shè)計的研究分析開始于一系列的初步構(gòu)思
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渣渣水平只有翻譯些簡單的，估計還有許多的錯誤,，哈哈來個英語牛逼的大俠多譯點(diǎn)
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作者: 左次無咎 時間: 2016-9-26 15:13
樓主,，我愛你，謝謝嘍,，努力中
作者: 掛726面 時間: 2016-9-26 15:14
When we pass from high school to university we bring with us the idea that answers are obtained by engineering calculations. We use analytical formulas and we are educated to believe that the results are either right or wrong – there is no in between and no grey areas.
1 s3 F1 n+ k. u/ j& |6 S' N, h1 W當(dāng)我們從高中進(jìn)入大學(xué) 我們帶著我們自己的想法用工程計算得到答案,。我們教育讓我們相信我們使用公式分析的結(jié)果要么是對的要么是錯的-在它們之間沒有 灰色地帶（我的理解就是模棱兩可）.
作者: UGAIHAOWY 時間: 2016-9-26 16:17
What came first, the chicken or the egg? 先有雞、還是先有蛋,？; |! w' X, s# A! ]# x
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It is a vicious circle: we need a complete design in order to test it, yet we cannot complete the design without calculating it. How do we break this vicious circle? By guessing our way to the design! By experience, by rules of the thumb and by rough calculations based on preliminary design ideas and sketches!
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3 ^0 O# s: @& Y g這是個死循環(huán)： 我們需要完成一個完整的演算過程來驗(yàn)證它,，然而這個是永遠(yuǎn)算不完的！ 那我們?nèi)绾未蚱七@個循環(huán)呢,？只能有理有據(jù)的猜了,！ 根據(jù)經(jīng)驗(yàn)得,，這個猜想只能靠經(jīng)驗(yàn)法則和模糊計算來驗(yàn)證了！
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Don’t forget that these early assumptions can be revisited and recalculated but at least they allow us to begin the process., B) [, U }, \! W/ r& P
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我們得牢記這些先人的猜想,，因?yàn)橄扔胁孪氩拍苡序?yàn)證,，即使它需要反復(fù)驗(yàn)和算！
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感覺愧對老師和她的80分,！
作者: 宋仲龍 時間: 2016-9-26 16:19
當(dāng)我們從高中步入大學(xué)之后,，我們便形成了這樣一種概念，即結(jié)果都是經(jīng)過工程計算得來的,。學(xué)習(xí)中通過方程分析計算得出的結(jié)果非對即錯,，答案是唯一的，這使得我們認(rèn)為實(shí)際亦是如此,。學(xué)生在處理問題時慣于把相關(guān)因素都考慮進(jìn)去,，我甚至記得自己判斷答案正確與否是根據(jù)有沒有把題目給定的相關(guān)數(shù)據(jù)都利用上了沒有。然而我們真的需要把方方面面都考慮到才能得出結(jié)果嗎,？* `/ i2 e( M T$ Q) { N1 A
現(xiàn)實(shí)問題并非如此,。通常來說，我們掌握的資料并不完善,，計算過程也不是一成不變的,。學(xué)生們曾經(jīng)不止一次得問我，設(shè)計齒輪時應(yīng)以齒的強(qiáng)度為準(zhǔn)還是以齒面的疲勞強(qiáng)度為準(zhǔn),。實(shí)際上兩個都可以作為齒輪設(shè)計的準(zhǔn)則,，而優(yōu)先選用最可能導(dǎo)致齒輪最先失效的強(qiáng)度作為設(shè)計的準(zhǔn)則。作為學(xué)生去理解它還是非常困難的,，還需謹(jǐn)慎區(qū)別,！
作者: 淡然 時間: 2016-9-26 16:31
What came first, the chicken or the egg?
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It is a vicious circle: we need a complete design in order to test it, yet we cannot complete the design without calculating it. How do we break this vicious circle? By guessing our way to the design! By experience, by rules of the thumb and by rough calculations based on preliminary design ideas and sketches!
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Don’t forget that these early assumptions can be revisited and recalculated but at least they allow us to begin the process.
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. U$ |2 W, g8 }7 s) K/ }4 E4 v" g先有雞還是先有蛋？
g; k* L* N6 P: P2 R 這是一個惡性循環(huán),，我們需要一個完整的設(shè)計來檢驗(yàn)我們的理論,。但沒有計算之前，我們又無法完成這個設(shè)計,。怎樣才能打破這種惡性循環(huán)呢? 只能靠假設(shè),，靠經(jīng)驗(yàn)以及”拇指法則“和建立在初步設(shè)計思路和草圖上的粗略的計算。
& l$ K7 x; v* _% {% |! u 雖然,，這些早期的假設(shè)還需要后來的重新驗(yàn)證和計算,，但至少憑借這些資料，我們可以開始進(jìn)行設(shè)計,。
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對英語比較有興趣,，但基礎(chǔ)不好，算積極參與吧。
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作者: 左次無咎 時間: 2016-9-26 16:48
+ z& \; j# i, }0 H' w E* V我要好好學(xué)英語,，掙錢,，養(yǎng)你
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作者: 水秀天藍(lán) 時間: 2016-9-26 17:26
淡然 發(fā)表于 2016-9-26 16:31
0 ^' o* f: \" g. J; J* }8 t' WWhat came first, the chicken or the egg?+ F1 w3 t# U$ l- `3 s' m# [
( M; U- z) J# I( b3 T [5 o; nIt is a vicious circle: we need ...
據(jù)說是先有雞，然后才有蛋,。
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作者: 貝XB2016 時間: 2016-9-26 18:34
么么么么么么么么噠
作者: 燃溪 時間: 2016-9-26 21:00
There are many ways to fail (but it only takes one)
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While teaching strength of bolts I once calculated a bolt for a number of different possible failure modes. I calculated for the “standard”, the pull strength of the core for the less common shaving of the threads and also for shearing of the head and a few more bizarre possible modes. I showed that, although all are possible, the standard bolts will nearly always fail at the core first. However, under certain conditions (too few mating threads, a weak mating material, etc) the threads might shave first. Confused? Let me explain….+ e, Q: Q7 o) |5 ~
, J9 E" Z3 w" V v( \* {失效的形式有許多種（但總歸發(fā)生其中一種）! i3 o6 D+ U( N
當(dāng)我講解螺栓的受力的時候,，曾經(jīng)對一個工作中的螺栓，從不同的失效形式上計算過,。標(biāo)準(zhǔn)失效形式——螺栓桿的極限拉力拉力,，螺紋的剪力（這個不太常見），螺栓頭的所受的切向力和其他一些不尋常的失效形式,。我這么做，是為了讓學(xué)生了解到,，雖然螺栓失效的形式多種多樣,，但是大部分情況下，它總是在螺栓桿處首先出現(xiàn)問題,。然而,，在某種特殊的條件下（旋入螺紋太少，被連接件強(qiáng)度太低,，等等）,，螺紋會首先被剪短。覺得困惑了嗎,？我們可以這樣來解釋：……
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作者: 掛726面 時間: 2016-9-27 16:08
掛726面 發(fā)表于 2016-9-26 15:142 h0 K$ J0 _' m7 M' `7 Z* _8 z
When we pass from high school to university we bring with us the idea that answers are obtained by e ...
! @6 F& a3 \4 h8 i/ H) Z2 x英語大渣渣,，受教了 謝謝1 e0 Y7 c: ^$ w W7 F
作者: zhumao6011 時間: 2016-9-28 08:30
1.不要相信他們在學(xué)校教你的任何事，真正的生活是非常不同的9 _% \$ m5 M5 l4 o) L) F
2.你應(yīng)當(dāng)馬上拋棄認(rèn)為設(shè)計問題只有一種正確解答的這種認(rèn)識,，讓你的大腦對各種觀點(diǎn)敞開大門,。
* w- j+ P% S) h4 L* R q3.設(shè)計失敗會有很多不同的形式，所有這些都應(yīng)當(dāng)被考慮,。# t2 h9 g$ f- U" X2 h; ]
4.什么先出現(xiàn),？先有雞還是先有蛋？一個假想設(shè)計的分析總是從可以調(diào)節(jié)的假設(shè)范圍開始的,。' y8 t! k+ B3 `/ }
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作者: 滾刀魚 時間: 2016-9-28 15:40
這只是一篇文章,？還是一本書？如果只是一篇文章,，請問樓主帖子里面已經(jīng)貼的完整了嗎,？) m: K4 K& D% I/ y# z& F0 R K+ M
如果是一本書，麻煩樓主能否告訴書名？
作者: 小師妹_c937B 時間: 2016-9-28 16:32
' o% r q5 b- G7 s6 H一篇文章，完整的,。
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作者: 所羅門_x 時間: 2016-9-29 10:54
公主稍等片刻,，我這就打開有道。,。,。。
作者: tedwu 時間: 2016-9-29 11:41
1. 不要再對學(xué)校里教的那套深信不疑,，現(xiàn)實(shí)生活往往大相徑庭,。
8 V' T+ u" I$ p4 \2. 立馬摒棄任何設(shè)計問題只有一個正確答案的錯誤想法，對所有備選方案敞開心扉,。: W; ]5 v h5 b% N1 {" ?
3. 設(shè)計失效多種多樣,，考慮上需面面俱到。
+ P! q) q# o2 j4 H- Y4. 無需糾結(jié)于雞先還是蛋先的悖論,，設(shè)計一定基于可修正的假設(shè),。9 s% c3 i) _; d8 d7 S8 ]7 w2 n
象牙塔中和現(xiàn)實(shí)生活問題解決的差異9 t/ q) j# B7 X w! U
從高中進(jìn)入大學(xué)的時候，我們被灌輸了這樣一種思想—通過工程計算來獲得答案,。 我們使用分析公式并且被諄諄教誨以至于對結(jié)果只有好壞（沒有含混和灰色地帶）的觀點(diǎn)深信不疑,，我們對問題的相關(guān)數(shù)據(jù)完全齊備的情況習(xí)以為常。我甚至對通過驗(yàn)證是否使用問題的所有數(shù)據(jù)來檢查我的答案記憶猶新-是否總是需要使用所有的數(shù)據(jù)來獲得答案,？
# w( h4 L6 g$ W這絕對與世隔絕,。數(shù)據(jù)從來不是“既定的”，而通常是不完整的,，絕無僅有的“正確”公式也實(shí)在不必要,。曾經(jīng)有諸多學(xué)子問我采用兩個不同的公式（輪齒強(qiáng)度和齒面疲勞）的哪一個來計算齒輪，實(shí)在難以讓他們理解兩個公式都是“正確的”并且應(yīng)當(dāng)以最壞情況來計算,。6 }2 O2 r) v1 K9 |/ c
失敗若水有三千（但你只能取一瓢）
W# _8 @2 W! T/ B% i# Y% ]我曾經(jīng)在教授螺栓強(qiáng)度的時候計算過諸多不同的失效模式下的螺栓強(qiáng)度,，我按照“標(biāo)準(zhǔn)”的方法，在螺牙剪切和螺栓頭剪切很少發(fā)生并且各種可能的稀奇古怪的模式基本沒有的情況下只計算在螺桿的強(qiáng)度,。 我表明了雖然一切模式皆有可能,，但標(biāo)準(zhǔn)的螺栓基本上都首先在螺桿處發(fā)生破壞。即便如此,，在某些情況下（比如嚙合螺牙太少,，貼合面太弱等等）螺牙可能首先發(fā)生破壞,。覺得又說越亂，待我分解如下：
( ]" B" {! H( t5 j- d對其他可能的失效模式置若罔聞是非常危險的,，第一架英國噴氣式飛機(jī)Comet的設(shè)計師們就于50年代早期付出飛機(jī)失事和生命消隕的巨大代價,。
# j2 v% D, `( U* J7 B; O7 |+ j基于現(xiàn)實(shí)生活設(shè)計的風(fēng)險; P4 I/ @0 Y; a, D
吃頭啖湯總是有風(fēng)險的，高飛的噴氣式飛機(jī)和鋁材的應(yīng)用在當(dāng)年都非常新穎,。英國的工程師們也未意識到重復(fù)解壓載荷和應(yīng)力集中對鋁材機(jī)身的疲勞強(qiáng)度的影響,，只計算靜載遠(yuǎn)遠(yuǎn)不夠。$ v. O8 s+ D" j3 u2 Q: O
那么當(dāng)時他們是如何計算機(jī)身的,？在當(dāng)時計算機(jī)尚在襁褓之中,，F(xiàn)EA程序也尚未開始書寫。他們不得已使用應(yīng)力公式和手工的結(jié)構(gòu)設(shè)計工具,。即便在當(dāng)今,，如無強(qiáng)大的計算機(jī)和程序，也難題分析復(fù)雜程度堪比機(jī)身的結(jié)構(gòu),， 我們雖有更好的研究工具但舊問題和挑戰(zhàn)依然揮之不去,。
% r3 z, h/ k( O2 z& w' Y技能、常識和耐心: U% Q5 S, U2 l9 |9 a* f3 X
他們必須要做的就是簡化,，每次計算結(jié)構(gòu)上的構(gòu)件然后對實(shí)際的零件和組件進(jìn)行測試,。這種方法實(shí)際上是采用計算和實(shí)驗(yàn)測試的組合來驗(yàn)證設(shè)計。我們必須承認(rèn)雖然他們工具粗陋但活干的很漂亮,。
5 G0 h" m0 S- v6 U9 F; B' ` T我們意欲相信我們在今天的設(shè)計上做得好得多，實(shí)際上是我們的工具比他們的好得多同時絕大多數(shù)原理近乎雷同,。我們用FEA程序構(gòu)建模型和進(jìn)行測試,。在計算模型而非硬件模型上進(jìn)行測試僅僅是時間和成本的差別， 在測試和分析之前我們?nèi)匀槐仨毺峁┩暾脑O(shè)計,。. o2 [: U, V* r
先有雞還是先有蛋,？# E( b0 ^+ t4 t6 w6 C0 g! x
我們陷入了一個惡性循環(huán)：為測試我們需要一個已經(jīng)完成的設(shè)計，但不經(jīng)過計算我們就沒法完成設(shè)計,。怎么打破這個惡性循環(huán),？猜測！通過經(jīng)驗(yàn),、經(jīng)驗(yàn)法則和基于初步設(shè)計與草圖的粗略計算,。! i6 J ~, w: w' k4 B# g! u
記住：早期的假設(shè)是可以回訪和再計算的,，但至少這些假設(shè)讓我們可以開干了,。
作者: amone 時間: 2016-9-29 12:55
The risks of designing for the real world
在現(xiàn)實(shí)世界中進(jìn)行實(shí)戰(zhàn)設(shè)計的風(fēng)險
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It is always risky to design something new. High flying jets and the use of aluminium were pretty new in those days. British engineers also failed to realise the effects of repeating decompression loads and stress concentrations on the fatigue strength of the aluminium airframe. Calculating for static loads was just not enough.
設(shè)計新穎的產(chǎn)品總會伴隨著風(fēng)險。如今,，（作者用were pretty,，過去時，應(yīng)該是在過去談?wù)摦?dāng)今）高速噴氣式飛機(jī)和鋁材的應(yīng)用仍然十分前沿。英國的工程師（應(yīng)該指羅羅航空發(fā)動機(jī)公司）對鋁合金機(jī)體的疲勞強(qiáng)度和重復(fù)減壓負(fù)荷以及應(yīng)力集中的關(guān)系仍然是認(rèn)識不足,。對靜載荷的計算仍然不充分,。
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How did they calculate their airframe then? Computers were still in their infancy and FEA programs were not written yet. They had to use stress formulas and manual structural analysis tools. Even today, with our powerful computers and programs, it is not easy to analyse a structure as complex as an airframe. We have better research tools but the old problems and challenges are still there.
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那么他們是如何計算機(jī)體的強(qiáng)度？當(dāng)時計算機(jī)還只是個雛形,，有限元分析等計算工具尚未發(fā)明,。他們只能手動進(jìn)行受力分析計算。即便是今天,，手握強(qiáng)大的計算工具和軟件,，對機(jī)體這樣復(fù)雜結(jié)構(gòu)進(jìn)行（力學(xué)/結(jié)構(gòu)）分析仍然是困難重重。研發(fā)使用的計算工具有了充足的進(jìn)步但是那些老大難的問題依然沒有解決. |+ x6 {. y1 z9 w! B
作者: 小師妹_c937B 時間: 2016-9-29 13:33
tedwu 發(fā)表于 2016-9-29 11:41# B9 }0 c4 W- Q" M$ ?6 W
1. 不要再對學(xué)校里教的那套深信不疑,，現(xiàn)實(shí)生活往往大相徑庭,。
+ @& H, {* d& E. B2 d2 i' R2. 立馬摒棄任何設(shè)計問題只有一個正確答案的 ...
1 @9 `! C I' X9 A A8 @# t大俠的翻譯已經(jīng)可以當(dāng)參考答案了，文字功底很深厚
作者: jcj0512 時間: 2016-9-29 15:13
我正在努力的翻譯呢,，確被人搶先了,，算了，不發(fā)了,。呵呵
作者: 彷徨2014 時間: 2016-9-29 18:26
這就是在學(xué)英語了吧
作者: andyany 時間: 2016-9-30 09:21
樓主這篇文章很不錯,，是從哪看來的呢？0 }* e% ?* j+ l7 O+ w( ^
我很想知道,。謝謝,！
作者: 小師妹_c937B 時間: 2016-9-30 09:27
3 d) o2 P8 N! cengineeringclicks.com
作者: 荷鋤望月 時間: 2016-9-30 20:44
1,、Don't believe everything they teach you at school, real life is very different!, M2 T3 j1 S0 a7 h! s# V& ~* Z- @
勿信學(xué)校所授,，現(xiàn)實(shí)大相徑庭。
1 k- C; h( p P" l7 S' A6 e( Y2,、You should immediately dismiss from your head the idea that there is only one right answer to any design question. Keep your mind open to all options.
- C, P- W* w0 p拋卻心中執(zhí)念,，設(shè)計之旨，絕非唯一,。包容并蓄,，方得其趣。
, u( N& Y# I m3,、Design failures can have many different forms and all should be considered.
" c, J" K" B2 V3 I設(shè)計之過,，成因繁多，宜細(xì)審視,，不可偏廢,。
* L( j$ N6 x+ n. v* Z l @/ a8 W8 K6 y4,、What came first, the chicken or the egg? The analysis of a hypothetical design will always start with a range of assumptions which can be adjusted
) r: I* g/ i, | H. k0 X雞生蛋乎？或否焉,。假定設(shè)計分析常始于假想,，亦可反矣。
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既然是從業(yè)五十余年,，就翻得有些古味,。剛看到文章，加班累了,，權(quán)當(dāng)換換腦子,。只為戲言，權(quán)當(dāng)一樂,。
作者: menglingtao 時間: 2016-10-1 13:51
沒學(xué)好,，我回去好好學(xué)英文。
作者: 天天天藍(lán)_ 時間: 2016-10-2 22:59
只能膜拜了
作者: 血刃x 時間: 2016-10-3 15:34
1.別信學(xué)校的那一套,，現(xiàn)實(shí)是不一樣的（學(xué)校是紙上談兵,，哈哈哈哈哈）3 Y( S$ h6 A4 A$ s1 N4 ~* V
2.你應(yīng)該做的是思考更多的方案，摒棄答案唯一論, [- G2 S; A0 q; {! c' D& G
作者: 血刃x 時間: 2016-10-3 15:41
荷鋤望月 發(fā)表于 2016-9-30 20:44
6 M5 `8 X& n1 U1,、Don't believe everything they teach you at school, real life is very different!
! ]: ^- J) `, S- [! g勿信學(xué)校所授,，現(xiàn) ...
雞生蛋否，蛋生雞否,，能否告訴我是先有雞還是先有蛋
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作者: jack03223 時間: 2016-10-3 18:35
進(jìn)到英語吧了,？
作者: liuchang-zhiyun 時間: 2016-10-5 09:19
10歲上班，從業(yè)50年,，正好60歲,。
作者: 屏風(fēng)ing 時間: 2016-10-5 11:07
大概看了一遍，翻譯不出來喲,，看來四級的水平在這里就是菜鳥了
作者: 彷徨2014 時間: 2016-10-5 17:26
1、學(xué)校教的東西不要所有的都相信,，現(xiàn)實(shí)生活中遇到的會有很大的不同,。
- @" ?+ F3 X* J& I4 U2、設(shè)計中遇到的問題并不僅僅只有一種正確答案,，思維要開放,。
; S- l6 D: K5 w. R; Y4 P3、設(shè)計失敗包含很多因素,，考慮問題要全面,。
, _6 U( U% l# A) m% b5 T4、先有雞還是先有蛋,。分析所設(shè)想的設(shè)計方案時,，往往是從調(diào)整設(shè)想范圍開始的,。
作者: 血刃x 時間: 2016-10-6 12:57
. l* @! E2 C1 z嗯,，可能是從毛毛蟲變來的
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作者: andyany 時間: 2016-10-9 13:51
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這個網(wǎng)站怎么注冊呢？
作者: tedwu 時間: 2016-10-20 11:56
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班門弄斧,，謝謝鼓勵。7 u/ V I( E g' z4 X) p+ ~
作者: dick3848 時間: 2017-9-18 11:07
看不懂
作者: chnalzha 時間: 2017-11-28 12:26
技能,，常識和耐心
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