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问题 填空题
lim
n→∞
(
n2+2n
-n)=______．
答案

原式=

lim
n→∞
(
n2+2n
-n)(
n2+2n
+n)
n2+2n
+n

=

lim
n→∞
2n
n2+2n
+n

=

lim
n→∞
2
1+
2
n
+1

=1．

故答案是1．

阅读理解

阅读理解。

     I'm Mary. I'm an English girl. My age is twelve. I was born (出生) on May 17th , 1991. I learn

 Chinese at Beijing No.3 Middle School. I have a good friend. Her name is Lucy. She is twelve, too. We

 are in the same (同样的) grade (年级). But we are not in the same class. I'm in Class Two, and she is in

  Class Three. We have the same Chinese teacher (教师). Her name is ZhaoYing. We all like her. Lucy's

  father teaches English in China, Lucy's mother teaches us English . And she has a sister. Her name is Lily.

  She is only a year- five -old girl.

1. Who has a sister?

    A. I don't know  

    B. Mary  

    C. Chinese teacher

    D. Lucy

2. Mary and Lucy are _____.

    A. classmates

    B. sisters  

    C. brothers

   D. friends

3. Lucy was born _____.

    A. on May 17th , 1990

    B. on May 17th ,1991

    C. Sorry, I don't know.  

    D. in May 17th, 1990

4. Mary and Lucy have the same _____.

    A. grade  

    B. Class  

    C. age  

    D. A and C

5. Now Lucy's parents are in _____, They teach _____.

    A. England, English

    B. China, English

    C. England, Chinese

    D. China, Chinese
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单项选择题

关于曝气沉砂池进出水的设计，下述说法中正确的是（）。

A．进水方向与池中旋流方向一致，出水方向与进水方向垂直，并宜设挡板

B．进水方向应与池中旋流方向垂直，出水方向与进水方向一致，并宜设挡板

C．出水渠道宽度应为进水渠道宽度的2倍

D．出水渠道与进水渠道的夹角应大于270。
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