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1.value n. 价值 |
valuable adj. 贵重的; 很有价值的 |
valueless adj. 无价值的; 没有用处的 |
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2. survive v. 继续生存或存在 |
survival n. 存活; 幸存 |
survivor n. 幸存者 |
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3. decorate v. 装饰 |
decoration n. 装饰; 装潢 |
decorative adj. 装饰的; 作装饰用的 |
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[练习]用括号内所提供词的适当形式填空 1) The jawbone was our most _________ discovery. (value) 2) They have ordered software to the _______ of 700. (value) 3) He thinks our advice is _________, so he won’t take it. ((value)) 4) Many strange customs have __________ from earlier times. (survive) 5) This ceremony is a _________ from pre-Christian times. (survive) 6) She is the only ________ in the accident. (survive) 7) When will they finish the ________ of the bathroom? (decorate) 8) The building was _________ with flags. (decorate) 9). The coloured lights are very _________. (decorate) Keys: 1) valuable 2) value 3) valueless 4) survived 5) survival 6) survivor 7) decoration 8) decorated 9). decorative |
20.(16分)某班40个学生平均分成两组,两组学生某次考试的成绩情况如下表所示:
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组别 |
平均数 |
标准差 |
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第一组 |
90 |
4 |
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第二组 |
80 |
6 |
(1)证明: 一组数据
的标准差为
;
(2)求这次考试全班的平均成绩和标准差.
19.(16分) 计算式子
,求满足上述式子的最小正整数n的算法如下,试补全下面伪代码并根据左面第一个算法画出流程图。
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解:(1) (2) (3) (4) (5)
流程图为: