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问题 选择题

1998年中国十大科技成果之一是合成纳米氮化镓．已知镓（Ga）原子结构示意图为，氮原子结构示意图为．则氮化镓的化学式是（　　）

A．Ga3N2

B．Ga2N3

C．GaN

D．Ga5N3

答案

由镓（Ga）原子结构示意图可知，在反应过程中它容易失去三个电子而达到稳定结构，形成了带三个正电荷的离子；氮原子的最外层电子数是5，易得到三个电子，形成了带三个负电荷的离子．则Ga为+3价，N为-3价，故氮化镓的化学式是GaN．

故选：C．

阅读理解
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Family member
What does he/she look like?
My father
My father is very tall. He has curly hair. He's handsome
My mother
My mother is not beautiful. She is short. She is only 1.5
metres. She has black hair. And she is fat.
My sister
My sister is a lovely girl. She has long curly hair. She's of
medium build.
My brother
My brother looks like my mother. He is short, too. He is
heavy.
1. What does the writer's father look like? 
A. He is very short.    
B. He is short and has black hair.    
C. He's of medium build.    
D. He is tall and has curly hair.
2. Who are short and heavy?
A. The writer's mother and brother.    
B. The writer's mother and father.    
C. The writer's father and sister.    
D. The writer's father and brother.
3. Does his brother look like his father?
A. Yes, he does.                
B. No, he doesn't.    
C. Yes, he doesn't.              
D. No, he does.
4. What does the writer look like?
A. He is handsome.    
B. He is heavy and tall.    
C. He has long curly hair.    
D. We don't know.
5. According to the passage, which is RIGHT?
A. There are four people in the writer's family.    
B. The writer's mother is a beautiful woman.    
C. The writer's father and sister have curly hair.    
D. The writer's brother looks like his sister.
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填空题

我国少数民族中人口最多的是（），人口最少的是（）。
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