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1概率的期望问题有3个球,4个盒子,盒子编号为1,2,3,4,将球逐个独立随机地放入4个盒子中.设X为
概率的期望问题有3个球,4个盒子,盒子编号为1,2,3,4,将球逐个独立随机地放入4个盒子中.设X为在其中至少有一个球的盒子的最小号码（如X＝3表示第一、二号盒子空着）,球X的期望.我算的是7/4、但答案是25/16
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2几道解三角形 数列的题1.在三角形abc中,若sinA=2cosBcosC,则tanB+tanC=?
几道解三角形 数列的题1.在三角形abc中,若sinA=2cosBcosC,则tanB+tanC=?2.在三角形abc中,若lgsinA-lgscosB-lgsinC=lg2,则三角形abc的形状是?3.在三角形abc中,若tan（A-B）/2=（a-b）/（a+b）,则三角形abc的形状是?4.在公比为整数的等比数列中,若a1+a4=18,a2+a3=12,则该数列前八项之和为?
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3Which of the following about Seamus Heaneys poetry creation is TRUE？A．His poems usually ap
Which of the following about Seamus Heaneys poetry creation is TRUE？
A．His poems usually appear in poetry collections.
B．His poems mainly center on the darkness of life.
C．He gives poem readings in public sometimes.
D．His poetry creation is improved after his winning of the Nobel Prize.
请帮忙给出正确答案和分析，谢谢！
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4三角形三个角a,b,c的比分别是3：4：5,且a+1可以组成等比数列,求三个边是多少?（题目记不清了
三角形三个角a,b,c的比分别是3：4：5,且a+1可以组成等比数列,求三个边是多少?（题目记不清了）我同学写的但看不明白设a+1,b,c的公比为xa：b：c=3：4：5a/（a+1）x的平方a/（a+2）的平方=3/5x=5/4a=15a=15,b=20,c=25能不能帮我详解?
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5当有1000元让步空间时,下列让步策略描述正确的是？A、所有答案都不对B、可以使用600,400,0,0大跨
当有1000元让步空间时,下列让步策略描述正确的是？
A、所有答案都不对
B、可以使用600,400,0,0大跨度的让步策略
C、可以使用500,200,100,50均匀的让步策略
D、可以使用250,250,250,250 平均幅度的让步策略
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6解题：数列题7 7 9 17 43 （ ） a.119 b.117 c.123 d.121
解题：数列题7 7 9 17 43 （ ） a.119 b.117 c.123 d.121
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7He will never be bullied into any change of his______.A．statusB．standpointC．sympathyD．tend
He will never be bullied into any change of his______.
A．status
B．standpoint
C．sympathy
D．tendency
请帮忙给出正确答案和分析，谢谢！
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8We believe an offence was committed______EU regulations.A．withB．overC．underD．on
We believe an offence was committed______EU regulations.
A．with
B．over
C．under
D．on
请帮忙给出正确答案和分析，谢谢！
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9题目是关于数列的各项均为正数的数列｛an｝中,s1＞1且6sn＝(an+1)(an+2),求an?(
题目是关于数列的各项均为正数的数列｛an｝中,s1＞1且6sn＝(an+1)(an+2),求an?(注：(an+1)(an+2)中的加号并不是角标而且加在an的后面!)
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10We feel sorry for being unable to entertain your request for offering a free car. The unde
We feel sorry for being unable to entertain your request for offering a free car. The underlined part means
A．surprise
B．contest
C．meet
D．gain
请帮忙给出正确答案和分析，谢谢！
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