Good teachers ,records ,tapes ,books ,and dictionaries will help .

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• 短文改错,I like reading because books are good teachers and help friends.When I am a child,I got into the habit of read.In t
• 短文改错,I like reading because books are good teachers and help friends.When I am a child,I got into the habit of read.In the past years,I have read many the books.Reading helps me relax and see the world different ways.It also develop my interests and enriches my knowledge.There are much books that we can read,and different people have our own favorite ones.I like to read books on music,for it is an important part of life.Learn some basic information ab
• 英语翻译So it is ____(A.hard B.easy C.funny D.silly ) to say that learning English is easy,because a good command of English _____(A.depends B.tries C.has D.takes) upon a lot of practice.And practice needs great effort and ___(A.uses B.takes C.gets D.spends) much time.Good teachers,records,tapes,books,and dictionaries will help.But they cannot do the student's work for him.
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• 关于大一概率论与数理统计的问题~1、设随机变量X的分布律为P{X=（-1）j+1 3j/j}=2/3j,j=1,2,…说明X的数学期望不存在.2、设总体X~x2(n),X1,X2,…X10是来自X的样本,求E(X平均),D(X平均),E(S2).3、设在总体N(μ,σ2)中抽取一容量为16的样本.这里μ,σ2均为未知.(1)求P{ S2/Ơ2≤2.041},其中S2为样本方差；(2) 求D(S2).4、随机地取8只活塞环,测得它们的直径为（以mm计）74.001 74.005 74.003 74.001 74.000 73.998 74.006 74.002试求总体均值μ及方差σ2的矩估计值,并求样本方差S2.