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问题 填空题
已知两条直线l1：y=m 和l2：y=
8
2m+1
（m＞0），直线l1与函数y=|log2x|的图象从左至右相交于点A，B，直线l2与函数y=|log2x|的图象从左至右相交于C，D．记线段AC和BD在X轴上的投影长度分别为a 和b．当m变化时，
b
a
的最小值为______．
答案

设A，B，C，D各点的横坐标分别为xA，xB，xC，xD，

则-log2xA=m，log2xB=m；-log2xC=

8
2m+1
，log2xD=
8
2m+1
；

∴xA=2-m，xB=2m，xC=2-

8
2m+1
，xD=2
8
2m+1
．

∴a=|xA-xC|，b=|xB-xD|，

∴

b
a
=
2m-2
8
2m+1
2-m-2-
8
2m+1
=2m•2
8
2m+1
=2m+
8
2m+1

又m＞0，∴m+

8
2m+1
=
1
2
（2m+1）+
8
2m+1
-
1
2
≥2
1
2
×8
-
1
2
=
7
2
，

当且仅当

1
2
(2m+1)=
8
2m+1
，即m=
3
2
时取“=”号，

∴

b
a
≥2
7
2
=8
2
，

故答案为：8

2
．

单项选择题

按损失控制的目的不同，损失控制可以分为（）。

A.损失发生前、损失发生时、损失发生后

B.工程法和行为

C.损失预防和损失避免

D.损失预防和损失抑制
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填空题

Kofi Annan says helping survivors of last week’’s earthquake and (1)________in the Indian Ocean is (2)________. The United Nations secretary-general says countries that have offered aid must (3)________and provide it. The offers add up to around (4)________dollars. United Nations officials say (5) ________of that is needed during the next six months.The concern about offers of international aid is (6)________. For example, the earthquake in Bam, Iran, in (7)________of 2003 killed more than (8) ________people. Countries and groups offered hundreds of millions of dollars (9) ________. The United Nations says it has (10)________only about (11)________dollars in aid received so far. Governments and organizations that offered help (12) ________that, however.On (13)________Mr. Annan met with world leaders in Jakarta, Indonesia to discuss aid for (14)________. The leaders discussed and (15)________the idea of (16)________owed by affected nations. But the leaders did not say they would do so. Some said that (17)________to survivors would be more helpful.Representatives of (18)________countries and international organizations attended the meeting in Jakarta. Officials say they will cooperate to develop (19)________ for the Indian Ocean and the (20)________.
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