st
发帖数: 1685 | 1 I knew that his head got chopped off in the movie, but I didnot
recognize him. heeh. |
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l**g
发帖数: 2859 | 2 Take easy. In any country, you can meet very rude people. Don't be too
sensitive to racial difference.
In China, I guess you may have met a guy who yelled at you "XX(the name of a
place)Lao, Cao Ni Da Ye".
heeh.... |
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t**a
发帖数: 675 | 4 heeh.这个好办，参看那里野花索引里sanny的帖子就好了，哈哈
突然想起，有一次坐老板的车，他特详细地给我介绍了一种我们实验室附近的紫花，满
树的紫色，非常漂亮。后来我还专门查了wiki，不过没过几天就想不起名字了。哎，年
纪大了，
所以现在我干脆不记了，生活已经不容易了，不能太push自己了。赫赫 |
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b****q
发帖数: 24 | 8 NTU. singapore not bad, just like Shanghai,heeh |
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b***k
发帖数: 312 | 9 I seldom came this bbs leh, normally once per week.
no time at all, so busy....
no sunshine here, only rains and rains, faint. heehe |
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a******p
发帖数: 282 | 10 heeh,
我一周没有来，
不是我不想来，
实在没有机会呀。 |
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f*****x
发帖数: 545 | 12 heeh, similar feelling. |
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a*******g
发帖数: 4872 | 16 heeh, in HZ now..
I visited Paris and Lyon, the first feeling was that daytime was toooo short
(maybe because of winter? |
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a*******g
发帖数: 4872 | 17 heeh, long long story in my childhood |
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a*******g
发帖数: 4872 | 18 heeh, I also had the WII dance disk and played a lot before the TV when I wa
s in school |
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a*******g
发帖数: 4872 | 19 heeh, where did you leave Hangzhou?
In my memory, it was open when I was a little child. |
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a*****p
发帖数: 1285 | 20 thank you very much. i was thinking of the Spring reference. and I saw you
guys' posts. yea, i am going for in action now. heeh
the
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r******n
发帖数: 149 | 22 I*e^t =e^t if t is a matrix
heeh |
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b***k
发帖数: 2673 | 23 ☆─────────────────────────────────────☆
blook (布鲁克) 于 (Tue Mar 11 15:47:23 2008) 提到:
sum(k=1..n) k^3 = (sum k)^2 =( n(n+1)/2 )^2
TFC的书中说前一个等式可以几何法证明，是怎么构造的？
☆─────────────────────────────────────☆
redlemon (heehe) 于 (Tue Mar 11 16:18:12 2008) 提到:
因为
k^3= k^2 + k^2(k-1)= k^2 + k*(k*(k-1))/2 + k*(k*(k-1))/2
= k^2 + 2k*(sum k )
所以
sum_1^n k^3= sum_1^n(k^2 +2k*(sumk)))= (sum k)^2
几何解释这个式子就是说一个底面为 (sum_1^n k)\times (sum_1^n k), 高为1
的长方体体积等于 n个 边长为k 的立方体体积（这些立方体可以排列在刚才那个底 |
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e*a
发帖数: 749 | 26 来自主题: _D_SupportGroup版 - 谁安慰我一下 heeh
我想，要是遇见一个能让我笑的男生就好了 |
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