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问题 解答题
先化简，再求值：
x2-2x
x2-1
÷ (x-1-
2x-1
x+1
)，其中x=2cos45°+1．
答案

原式=

x(x-2)
(x+1)(x+1)
÷
(x-1)(x+1)-(2x-1)
x+1

=

x(x-2)
(x+1)(x+1)
÷
x2-1-2x+1
x+1

=

x(x-2)
(x+1)(x+1)
•
x+1
x(x-2)

=

1
x-1
，

当x=2cos45°+1=2×

2
2
+1=
2
+1，

原式=

1
2
+1-1
=
1
2
=
2
2
．

下表为1976～1990年苏联经济增长率(%)简表。其中，1990年经济发展出现负增长的原因是  （  ）

年份(年)1976～19801981～19851986～19891990
社会总产值4.23.31.8－2
国民收入4.33.21.0－4
劳动生产率3.33.1 －3
A.自然灾害造成的破坏              

B.戈尔巴乔夫经济改革不见成效

C.苏联解体导致的社会混乱          

D.赫鲁晓夫改革导致的混乱
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单项选择题

Aristotle was one of those who could found a civilization, and while he thought of education as both a social value and an end in itself, he ascribed its chief importance (21) what might be considered a third basic concept of education: to train the mind to think, (22) what it is thinking about. The key is not (23) it knows but how it (24) any new fact or argument. "An educated man," Aristotle wrote in On the Parts of Animals, "should be able to (25) a fair offhand judgment as to the goodness or badness of the method used by a professor in his exposition. To be (26) is in fact to be able to do this."
The Aristotle view of education as a (27) has become the conventionally worthy answer today (28) college presidents and other academic leaders are asked what an education should be. An educated man, says Harvard President Bok, (29) a deep breath, must have a "curiosity in (30) the unfamiliar and unexpected, an open-mindedness in entertaining opposing points of view, (31) for the ambiguity that surrounds so many important issues, and a willingness to make the best decision he can in the fact of uncertainty and doubt."
This is an approach that appears to (32) more importance to the process of learning (33) to the substance of what is learned. The very old notion of the generalist who could comprehend all subjects has (34) been an impossibility. To make matters (35) more difficult, the fields of knowledge keep changing.

A. when B. what C. how D. that
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