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问题 选择题

一元二次方程-3x2+3x+4=0，变二次项系数为正，且根不变的是（　　）

A．3x2+3x+4=0

B．3x2-3x+4=0

C．3x2+3x-4=0

D．3x2-3x-4=0

答案

方程的两边同时除以-1，得：

3x2-3x-4=0．

故选D．

改错题
改错题。
     It was sunny this afternoon. Mum and I go to        
the park where is near my home for a walk.          
When we were walking, I saw the little girl. She    
was eating a banana. After she finished eating them,
she threw the banana skin on the ground into the    
park. I walked over to pick it and told her it      
was wrong to do so. If all of us do like that,      
the park has become dirty. Then we can’t           
enjoy by ourselves in it. All of us must            
improve us environment and then we can             
make our environment clean but beautiful.           
1. _____　
2. _____　
3. _____　
4. _____  
5. _____  
6. _____  
    　　  
7. _____　                                                               
8. _____　
9. _____  
10. _____　
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单项选择题

国内生产总值是社会总产品价值中扣除( )后的余额。

A．增加值

B．价格上涨因素

C．中间投入价值

D．利率变动因素
查看答案