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问题 解答题
先化简(
1
x-1
-
1
x+1
)÷
x
2x2-2
，然后从1，-1，
1
2
中选取一个你认为合适的数作为x的值代入求值．
答案

原式=

x+1-x+1
(x-1)(x+1)
×
2(x+1)(x-1)
x

=

2
(x-1)(x+1)
×
2(x+1)(x-1)
x

=

4
x
，

当x=

1
2
时，原式=
4
1
2
=8．

单项选择题

踏步换齐步，听到‘前进’口令，继续踏（）步，再换跑步行进。

A、1

B、2

C、3

D、4
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填空题

Tragedies have a way of making people rethink their (1) and find a new focus. They make people think about what a society needs in order to (2) . The notion of doing something to take control of society or of our fate as humans might be dated back to ancient times of the (3) . Now, in the early 21st century, " social (4) " are trying to take back some (5) over society’s direction once again. A social inventor is not necessarily a social (6) , a social (7) or someone who works in a (8) industry or invents new (9) and consumer products. A social inventor is using the power of (10) thinking, to come up with ideas for (11) in certain communities or sections of society. They have a vision of a (12) world and create new systems or practices. Their ideas may seem (13) or impossible. They are usually quite (14) people. But some of these creative thinkers have (15) and quietly changed the way we live. Social inventions do not have to be (16) . Sometimes they are new (17) for neighborhoods or communities, or even very (18) ideas. The idea of social inventions has become so popular in recent years. It shows how much people desire to make a (19) in our society and not remain (20) .

Tragedies have a way of making people rethink their (1) and find a new focus. They make people think about what a society needs in order to (2) . The notion of doing something to take control of society or of our fate as humans might be dated back to ancient times of the (3) . Now, in the early 21st century, " social (4) " are trying to take back some (5) over society’s direction once again. A social inventor is not necessarily a social (6) , a social (7) or someone who works in a (8) industry or invents new (9) and consumer products. A social inventor is using the power of (10) thinking, to come up with ideas for (11) in certain communities or sections of society. They have a vision of a (12) world and create new systems or practices. Their ideas may seem (13) or impossible. They are usually quite (14) people. But some of these creative thinkers have (15) and quietly changed the way we live. Social inventions do not have to be (16) . Sometimes they are new (17) for neighborhoods or communities, or even very (18) ideas. The idea of social inventions has become so popular in recent years. It shows how much people desire to make a (19) in our society and not remain (20) .
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