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问题 选择题

下列运算不正确的是（   ）

A．a5＋a5＝2a5

B．(－2a2)3＝－2a6

C．2a2·a-1＝2a

D．(2a3－a2)÷a2＝2a－1

答案

答案：B

分析：根据合并同类项的法则，负整数指数幂和同底数幂的运算法则，积的乘方法则，整式的除法法则进行计算即可．

解答：解：A、a5+a5=2a5，正确，不符合题意；

B、（-2a2）3=-8a6，错误，符合题意；

C、2a2?a-1=2a2-1=2a，正确，不符合题意；

D、（2a3-a2）÷a2=2a-1，正确，不符合题意．

故选B．

阅读理解

阅读小天地，根据文内容判断下列句子的正(√)误(×)。

      Lily and Lucy are classmates. They're in the same class. Lily is from the U. K. and Lucy is from the U. S. 

      Lucy usually walks to school. Her home is not far from school. She arrives at school at 8: 00 from Monday

to Friday. She likes to play the piano. 

      Lily usually goes to school by bus. But sometimes she rides her bike. She always has lunch at school,

because her home is far from school. She likes to play ping-pong. She usually plays ping-pong with her friends

after school.

( ) 1. Lucy and Lily are in different classes.

( ) 2. Lucy's home is far from school.

( ) 3. Lily usually goes to school by bike.

( ) 4. Lucy likes to play the piano.

( ) 5. Lucy and Lily are from the U. S.

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填空题

每次发生冲击地压后，矿冲击地压防治专门机构必须指定专人进行现场调查，（），（），并填写（）。
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