例7-4-6
北师大版四年级上册数学口算天天练100题及答案
北师大版四年级上册数学口算天天练100题及答案北师大版四年级上册数学口算天天练第一天1. 198 + 47 = _______2. 256 - 124 = _______3. 24 × 3 = _______4. 72 ÷ 6 = _______5. 在1、2、3、4、5、6中选择两个数字，可以组成的两位数有多少个？第二天1. 35 × 4 = _______2. 106 + 27 = _______3. 84 ÷ 6 = _______4. 379 - 286 = _______5. 小明有16个糖果，他给了好友4个，还剩下多少个？第三天1. 74 × 5 = _______2. 203 - 89 = _______3. 45 ÷ 9 = _______4. 59 + 36 = _______5. 甲、乙、丙、丁、戊五个人一起合作，共做了112个工作任务，每个人做了相同数量的任务，请问每个人做了多少个任务？第四天1. 84 ÷ 7 = _______2. 75 × 6 = _______3. 326 + 87 = _______4. 209 - 135 = _______5. 某商店的货架上摆满了6件衣服，其中有2件衣服是红色的，其他都是蓝色的，那么蓝色衣服的件数是多少？第五天1. 46 × 8 = _______2. 173 - 68 = _______3. 98 ÷ 7 = _______4. 205 + 176 = _______5. 小明携带120个苹果至市场出售，如果每袋装4个苹果，那么他最多能装多少袋？第六天1. 54 ÷ 6 = _______2. 87 × 7 = _______3. 432 - 178 = _______4. 94 + 205 = _______5. 雨伞工厂共生产了80把雨伞，其中有5把有缺陷需要报废，那么合格的雨伞有多少把？第七天1. 63 × 9 = _______2. 105 - 73 = _______3. 800 ÷ 8 = _______4. 187 + 295 = _______5. 有一本书共有264页，小明读了7天，每天读相同数量的页数，那么每天他读了多少页？第八天1. 74 ÷ 9 = _______2. 127 × 8 = _______3. 631 - 298 = _______4. 205 - 153 = _______5. 小华用一捆绳子剪下了8段相等的长度，每段长度是2米，那么这捆绳子总长是多少米？第九天1. 89 × 7 = _______2. 315 - 279 = _______3. 648 ÷ 8 = _______4. 96 + 205 = _______5. 有一桶水装满了24公升，小明用了6天时间用相同的办法排出了全部的水，那么每天他排出了多少公升的水？第十天1. 47 ÷ 8 = _______2. 59 × 7 = _______3. 948 - 367 = _______4. 205 + 189 = _______5. 现有30本书需要放入相同数量的书架，如果每个书架能放12本书，那么最少需要多少个书架？答案：第一天：1. 245 2. 132 3. 72 4. 12 5. 15个第二天：1. 140 2. 133 3. 14 4. 93 5. 12个第三天：1. 370 2. 114 3. 5 4. 95 5. 22个第四天：1. 12 2. 450 3. 413 4. 74 5. 4件第五天：1. 368 2. 105 3. 14 4. 381 5. 30袋第六天：1. 9 2. 609 3. 254 4. 299 5. 75把第七天：1. 567 2. 32 3. 100 4. 482 5. 8页第八天：1. 8 2. 1016 3. 333 4. 52 5. 16米第九天：1. 623 2. 36 3. 81 4. 301 5. 4公升第十天：1. 5 2. 413 3. 581 4. 394 5. 3个。
三垦vm06变频器使用说明书
章
4-6-2 选购件基板的安装方法.................................................................30 第
5 操作面板 .............................................................................31
第
5-1-2 操作面板 LCD 操作部分.................................................................32
3
5-1-3 操作面板 LED 显示部分.................................................................32
3-4-1 拆卸操作面板 ...........................................................................16 3-4-2 安装操作面板 ...........................................................................16
2 产品的确认和注意事项 .................................................................10
2-1 产品的确认 ..................................................................................10 2-2 型号的内容 ..................................................................................10 2-3 使用前的注意事项 ............................................................................11
第5章.病例对照研究(王建华)
第五章病例对照研究病例对照研究（case-control study）是分析流行病学方法中最基本、最重要的研究类型之一。
近年来，在经典的病例对照研究基础上又衍生出若干种新的方法，克服了经典方法本身的一些缺陷，大大丰富和发展了病例对照研究的方法和内涵，成为现代流行病学方法学进展的重要部分。
病例对照研究得到越来越广泛的应用，特别是在病因学研究中，不失为一个得心应手的工具。
第一节基本原理病例对照研究的基本原理是以确诊的患有某特定疾病的病人作为病例，以不患有该病但具有可比性的个体作为对照，通过询问、实验室检查或复查病史，搜集研究对象既往各种可能的危险因素的暴露史，测量并比较病例组与对照组中各因素的暴露比例，经统计学检验，若两组差别有意义，则可认为因素与疾病之间存在着统计学上的关联。
在评估了各种偏倚对研究结果的影响之后，再借助病因推断技术，推断出某个或某些暴露因素是疾病的危险因素，从而达到探索和检验疾病病因假说的目的。
这是一种回顾性的、由结果探索病因的研究方法，是在疾病发生之后去追溯假定的病因因素的方法，是在某种程度上检验病因假说的一种研究方法（图5-1）。
最早的病例对照研究见于1843年Guy向伦敦统计学会所做的报告，该报告分析了职业暴露与肺结核发生的关系。
最早的病例对照研究的概念见于Louis的著作（1844）。
但是符合现代病例对照研究概念的研究首推Lane Claypon（1926）报告的生殖因素与乳腺癌关系的研究。
二次世界大战后，病例对照研究方法的应用大大增加，比较著名的有Schreck和Lenowitz（1947）的包皮环切和性卫生与阴茎癌的关系；Hartwell（1947）对于输血与肝炎关系的研究；Doll和Hill（1950）关于吸烟与肺癌的研究。
20世纪60年代以来，病例对照研究方法日臻完善，应用日益普遍。
其中，孕妇服用反应停（thalidomide）与婴儿短肢畸形、母亲吸烟与先天性畸形、早产儿吸入高浓度氧与晶体后纤维组织增生症、经期使用月经棉与中毒性休克综合征、小剂量电离辐射与白血病、以及母亲早孕期服用雌激素与少女阴道腺癌等之间的关系，均是应用病例对照研究的经典范例。
专项突破6-四则混合运算和运算定律六年级下册小升初数学专项培优卷含解析
专项突破6-四则混合运算和运算定律六年级下册小升初数学专项培优卷（含解析）专项突破6 四则混合运算和运算定律【考点导图】【考点精讲】考点梳理知识要点高分妙招四则混合运算的顺序 1.没有活号的算式中只有加、减法或只有乘、除法按从左到右的顺序计算；算式中有加减法也有乘除法，先算乘除，后算加减。
2.有括号的，先算小括号里的，再算中括号里的，最后算括号外面的。
在四则混合运算中加减是第一级运算，乘除是第二级运算，要先确定好运算顺序，再计算。
基本运算定律加法交换律：a＋b=b＋a 加法结合律：(a＋b)＋c=a＋(6＋c) 乘法交换律：a×b=b×a 乘法结合律：(a×b)×c=a×(b×c) 乘法分配律：(a±b)×c=a×c±b×c 连减逆运算：a－b－c=a－（b＋c）连除逆运算：a÷b÷c=a÷（b×c）尽量选择最合适的简便方法，使计算迅速、准确【典型题目】一．选择题（共10小题）1．被减数、减数与差，这三个数的和是124，那么被减数是（）A．124 B．62 C．452．一根绳子长89米，第一次用去31米，第二次用去28米，现在的绳长比原来少了多少米？列式正确的是（）A．31+28 B．89﹣31﹣28 C．89﹣31+28 D．89﹣28+313．（2分）最接近70的算式是（）A．28+51 B．91﹣29 C．83﹣144．六年级（1）班有38人参加了美术兴趣小组和音乐兴趣小组，其中参加美术兴趣小组的有25人，参加音乐兴趣小组的有21人，两个兴趣小组都参加的有（）人。
A．6 B．7 C．8 D．95．明明家、君君家和学校的位置如图所示。
明明家离学校有900米，君君家离学校有600米，明明家和君君家的距离可能是（）米。
A．280 B．300 C．450 D．15006．19881989+19891988的个位数是（）A．9 B．7 C．5 D．37．下面的四个算式中“5”和“2”可以直接相加减的是（）A．465+278 B．3.59﹣1.2 C．D．8．用同一句口诀计算的式子是（）A．12÷6和3×4 B．36÷4和4×9 C．4×6和3×89．5个装的口罩一盒40元，奇奇买了4盒这样的口罩，付给售货员200元。
外研版(2024)七年级上册Unit 4-6 拓展阅读专练(含解析)
U4拓展阅读一、阅读理解[2023潍坊诸城期末改编]Almost everybody loves snacks(零食). When I first came to Beijing, I was surprised to see that some of my favourite snack brands(品牌) from back home were also in China. Many of them also have new flavours(口味) for the Chinese.For example, the Dove brand of chocolate has a green tea-flavoured chocolate bar(巧克力棒). The Lay's brand of potato chips has a cucumber(黄瓜) flavour. I find shrimp-flavoured(虾味的) snacks too. And of course, fast food restaurants like KFC also have their own Chinese food such as youtiao and porridge(粥).Some of these "Chinese" flavours are very good. The green tea-flavoured snacks tasted a bit odd(奇怪的) to me at first, but I like the taste now.By Mike 1.The underlined(画线的) phrase "from back home" in Paragraph 1 refers to(指代) .A. in the writer's familyB. in the writer's countryC. in his home in BeijingD. in another(又一) city in China2.What snack does the writer's country have?A. The Dove brand of chocolate.B. Cucumber-flavoured potato chips.C. Shrimp-flavoured snacks.D. Youtiao and porridge.3.What does the writer want to show with this story?A. Chinese people don't like American snack brands.B. Chinese people give new flavours to many snacks.C. Chinese tastes are odd and hard to understand(理解).D. Chinese snacks are not as healthy as those in the US.二、阅读理解I'm a middle school student. I like all my teachers, but my favourite teacher is Mrs Smith, my English teacher.Mrs Smith is from Africa. She likes China very much. She thinks China is great. She loves Chinese food. Hot pot is her favourite and she always enjoys it on Sunday.Sometimes she has bread and milk for breakfast. Mrs Smith has a daughter and a son. Her daughter is Mary and her son is Tim. They are in China, too. They are studying in the school now. Mary is in Grade 3 and Tim is in Grade 4.Mrs Smith is very busy, because we have English classes from Monday to Friday. But she is always nice and happy. All of us like her and her classes very much. She often plays English games and sings English songs with us. When we have questions, we like to ask her for help.I think I have the best(最好的)English teacher.1.Where is Mrs Smith from?A. China.B. Africa.C. England.D. America.2.What's Mrs Smith's favourite food?A. Hot pot.B. Bread and milk.C. Eggs and potatoes.D. Hamburgers.3.How many children does Mrs Smith have?A. One.B. Two.C. Three.D. Four.4.What grade is Tim in?A. Grade 3.B. Grade 4.C. Grade 5.D. Grade 7.5.What can we know from the passage?A. Mrs Smith teaches maths.B. The students don't like Mrs Smith.C. Mrs Smith only has one lesson on Saturday.D. The students like to ask Mrs Smith for help.U5拓展阅读一、阅读理解Hello! My name is Plato and this is my school timetable. Let's have a look!School TimetableMonday Tuesday Wednesday Thursday Friday 08:30-09:20 Maths IT Geography History Chinese 09:30-10:20 English Chemistry Maths English PE 10:30-11:20 History PE Chinese Chinese Maths 11:20-12:00 BREAK(休息)12:00-13:00 Art Music Science Music History 13:00-14:00 LUNCH14:00-15:00 Chemistry Science IT Geography Art1.When does Plato have Science?A. On Monday.B. On Tuesday.C. On Thursday.D. On Friday.2.What does Plato do at 13:30 every afternoon?A. He has lunch.B. He plays sports.C. He has a class.D. He has a sleep.3.How many maths lessons does Plato have in a week?A. Two.B. Three.C. Four.D. Five.二、阅读理解热点素材．．．．What do you think of "double reduction(双减)" policy? Our readers from Teens have their ideas. Here are four of them.Shen Yuzhe, 13, BeijingThe "double reduction" really helps me. Our homework is less than before. I can finish it at school. I'm also happy to find that there are fewer exams.Zhang Hangming, 13, TianjinThe best thing about the "double reduction" is that we have more time to do after-school activities(课后活动) such as dancing, volleyball and cooking. I can also learn a lot of things.Yu Zhiyue, 14, JiangsuWith the "double reduction", I have really got less homework to do. But I need to take an online class on the computer at home after I come back from school. I often feel tired. But I can still have happy weekends.Cui Ruqi, 12, LiaoningI have got more time to read books and play sports. The art subjects are becoming more important, so I need to learn music well. And I have less learning stress(压力) now.1.What happens to(发生) Shen Yuzhe with the "double reduction"?A. He has less homework and fewer exams now.B. He is sad to have fewer exams now.C. He has no homework and exams now.D. He has more homework and exams now.2.Who has to take online classes at home after coming back from school?A. Shen Yuzhe.B. Yu Zhiyue.C. Zhang Hangming.D. Cui Ruqi.3.Why does Cui Ruqi need to learn music well?A. Because art is becoming more important.B. Because her friends learn music.C. Because she is good at art.D. Because art is her favourite subject.4.What's the passage about?A. Homework.B. After-school activities.C. Hobbies.D. Changes(变化) in students' life.U6拓展阅读一、完形填空Animals are our friends. We should try to protect(保护) 1. I like animals. Let me 2you what animals our family members like. My father likes the 3 very much. He thinks the tiger is 4and it is the king of the beasts(兽中之王). My favourite animal is the panda. The panda is 5China. It is very cute. It likes 6bamboo. I don't 7the tiger. I think the tiger is a little scary(可怕的). My mother likes animals too. She keeps some 8, ducks and pigs in our yard(院子). The chickens and ducks can lay eggs. They like to 9around in the yard. But the pigs don't like to walk. They like to 10very much. And they also like to eat.They sleep and eat a lot. My grandparents keep some cows and sheep. After breakfast, my grandfather takes the sheep out and goes back home in the afternoon.1.A. it B. they C. them D. she2.A. tell B. say C. speak D. talk3.A. lion B. tiger C. monkey D. panda4.A. same B. tall C. strong D. short5.A. to B. with C. for D. from6.A. watching B. playing C. taking D. eating7.A. buy B. wash C. like D. stay8.A. cats B. chickens C. lions D. tigers9.A. run B. walk C. drink D. ask10.A. sleep B. sing C. work D. ride二、阅读理解Hamsters (仓鼠) are animals. They look very cute. Lots of people like to keep them as pets. They are very popular(受欢迎的) with children.Hamsters are beautiful. They are black, white, brown, red or a mix of those colours. Hamsters have tails, but theirs are very short. A hamster's tail is only about 1 cm long, but it can help the hamster to keep balance(平衡).Hamsters like eating fruit and nuts. Some people buy hamster mix at the pet shop. Hamsters have a funny eating habit. They like to store(储存) food in their cheeks (面颊). Please remember to give them much food. Then they can have enough food to store.Hamsters are good pets because they are easy to be taken care of. They do not need a lot of room. Hamsters usually live in cages (笼子). They can do many things in the cages such as eating and exercising.1.A hamster uses its tail to .A. get its foodB. keep balanceC. clean its cageD. keep warm2.The underlined word "mix" in Paragraph 3 is probably .A. a kind of food for hamstersB. a kind of hamstersC. the name of the pet storeD. a kind of toy for hamsters3.Where do hamsters like to store food?A. In their cages.B. Under their tails.C. In their cheeks.D. In their plates.4. According to(根据) the passage, which of the following is TRUE?A. All the hamsters are black or brown.B. Hamsters aren't easy to take care of.C. The hamsters never exercise in the cage.D. We can know the length (长度) of the hamster's tail.U4拓展阅读参考答案一、阅读理解【解题导语】本文介绍了Mike在中国发现的一些不同口味的零食。
应用统计学(第四版) 第6章案例题目及答案
第6章案例分析题
某电子厂商最近创造了一种新的本钱更低的生产其电子产品的方法，由于新方法可能会影响该电子产品的使用寿命，该公司想对新方法生产的电子产品进行检验，于是建立了如下的原假设和备择假设。
H()://,<0,:X _以2 >°
其中，H是原方法下生产的电子产品的平均寿命，是在新方法下生产出的电子产品的平均寿命。
从每种方法生产的电子产品中各随机抽取30个并对其试验，得到如下表所示的数据。
要求：
(1)在。
=0.05的条件下，得出假设检验的结论。
检验的P值是多少？
(2)考虑了新方法可以节约大量的本钱，重新选定。
的值，比方，。
=0.01,此时，原假设是否会被拒绝？两总体均值之差99%的置信区间是多少？
(3)增加样本容量或改进生产过程减小产品寿命的方差，会不会增加或降低犯第I类和第II 类错误的概率？。
概率论1.5
即0.996n＝0.01 lg 0.01 故n = ≈ 1150 lg 0.996
= 1 − 0.996n ＝0.99
例3 甲、乙、丙3部机床独立工作，由一个工人照管， 某段时间内它们不需要工人照管的概率分别为0.9， 0.8及0.85。求在这段时间内有机床需要工人照管的概 率以及机床因无人照管而停工的概率。 解：用A、B、C分别表示在这段时间内机床甲、乙、 丙不需要照管。 则A、B、C相互独立，且 P(A)=0.9 P(B)=0.8 P(C)=0.85 P( A + B + C) = P( ABC) = 1 − P( ABC) = 1 − P( A )P( B)P(C) = 1 − 0.9 × 0.8 × 0.85 = 0.388
(2)若事件A与B独立，则A与B， A与B， A与B中的 每一对事件都相互独立。 证： P( AB) = P( A − AB)
= P( A) − P( AB) =P(A)-P(A)P(B)
=P(A)(1-P(B))
= P( A)P(B)
由(1)可知，A与B独立。
类似可证其它两对事件独立。
(3)若事件A1,A2,…,An相互独立，则有 P(A1…An)=P(A1)…P(An) 证：P(A1…An)＝P(A1)P(A2|A1)…P(An|A1…An-1) 而P(A2|A1)=P(A2),…,P(An|A1…An-1)=P(An) 故P(A1…An)＝P(A1)P(A2)…P(An)
在实际应用中,往往根据问题的实际意义 在实际应用中 往往根据问题的实际意义 去判断两事件是否独立. 去判断两事件是否独立 例如 甲命中}, 甲、乙两人向同一目标射击，记 A={甲命中 乙两人向同一目标射击， 甲命中 B={乙命中 ，A与B是否独立？ 乙命中}， 与 是否独立 是否独立？ 乙命中 由于“甲命中”并不影响“乙命中” 由于“甲命中”并不影响“乙命中”的 概率，故认为A 独立 概率，故认为 、B独立 . （即一事件发生与否并不影响另一事件发生 的概率） 的概率）
弹性力学-第4章 6-7 圆环
(4)针孔问题（应力集中）
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• 4-4, 4-7
作业
[例1]：曲梁纯弯曲问题的弹力解答
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qa r
r
验证圣维南原理，在 r a处，
应力很小，可以不计，即在内压 qa 作用下，b 处影响可不计。 作业：求出r=4b处应力的表达式
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3 页
解得
C1 = −3 C2 = 2
∴ yzi (n) = −3(− 2) 输入响应与输入无关
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注意
在求零输入响应时，要排除输入的影响 在求零输入响应时，要排除输入的影响—— 找出输入加上以前的初始状态。 找出输入加上以前的初始状态。
4 页
, 由初始状态再以x(n) = 0代入方程可以求出初始值 y(0) ≠ 0, y(1) ≠ 0。
第
例7-4-6
x 已知 (n) = (− 2) u(n)
n
1 页
LTIS的差分方程 y(n) + 3y(n − 1) + 2 y(n − 2) = x(n) − x(n − 1)
y(0) = y(1) = 0
求系统的零输入响应。 求系统的零输入响应。
x 时的解。 零输入响应 yzi (n),即当 (n) = 0时的解。
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y(n) + 3 y(n −1) + 2 y(n − 2) = 0
r 2 + 3r + 2 = 0 r1 = −2,
n
r2 = −1
n
yzi (n) = C1(− 2) + C2 (−1)
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求初始状态（0-状态）
是激励加上以后 不能说明状态 题目中 y(0) = y(1) = 0 ,是激励加上以后的,不能说明状态 是激励加上以 为0,需迭代求出 y(−1), y(− 2) 。 需迭代求出
2 页
n = 1 y(1) + 3 y(0) + 2y(−1) = (− 2)u(1) + (− 2) u(0)
0
0 + 0 + 2y(−1) = (− 2) + 1 = −1
1 ∴ y(−1) = − 2 0 1 y(0) + 3y(−1) + 2 y(− 2) = (− 2) u(0) + (− 2)− u(−1)
n=0
0 + 3 y(−1) + 2 y(− 2) = 1
5 ∴ y(− 2) = 4
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由初始状态（0-状态）定C1，C2
以y(−1), y(− 2)代入方程:
1 −1 −1 yzi (− 1) = C1 (− 2) + C2 (− 1) = − 2 y (− 2) = C (− 2)−2 + C (− 1)−2 = 5 1 2 zi 4