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问题 选择题

一只重500N的箱子放在水平地面上，甲学生用100N的水平力将箱子水平移动10m，乙学生把这只箱子匀速提高2m，那么，他们做功的大小是（　　）

A．相等

B．甲学生做功多

C．乙学生做功多

D．条件不够，无法确定

答案

甲同学做功：

W甲=Fs=100N×10m=1000J；

乙同学做功：

W乙=Gh=500N×2m=1000J；

∴W甲=W乙．

故选A．

选择题
把抛物线y=x2+bx+c的图象向右平移3个单位，再向下平移2个单位，所得图象的解析式是y=x2-3x+5，则有(   )

A.b=3，c=7
B.b=-9，c=-15
C.b=3，c=3
D.b=-9，c=21
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填空题

用适当的介词填空。

1. The students are listening ___   their teacher very carefully.

2.——I'm looking forward ____ taking a holiday in Hainan. 

   ——So am I.It's great to be ____ holiday there.

3. Sichuan is one of the largest provinces ____ China.  It's ____ the southwest ____ China.

4.——It's necessary ____ you to take exercise ____ the morning.  

   ——I agree ____ you. It's very kind ____ you to give me advice.

5. The moonlight comes in ____ the window and the room seems quiet and peaceful.
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