根据短文内容回答问题。

Dear Amy,

     How are you ? My name is David. I'm an American boy.  For me,  sports are fun. I have a collection

 of sports things. I have six basketballs , three tennis rackets, nine volleyballs, four soccer balls, and five

  baseballs. I play sports and I watch them on TV. Do you play sports?Do you have a sports collection?

1.  Is David American?                         

    _____ , _____ 

2. Are sports fun for David?                  

    _____  ,  _____ 

3. Does David have a collection of sports things?   

    _____  ,  _____ 

4. How many baseballs does he have?            

    _______________________.

5. Where does David watch sports ?  

    _______________________.       

设n_A为阿伏加德罗常数的值，下列叙述不正确的是（　　）

A．7 g C_nH_2n中含氢原子数为n_A

B．4．6 g NO₂．N₂O₄混合气体中含有中子数为2．3n_A

C．在反应5NH₄NO₃2HNO₃＋4N₂↑＋9H₂O中，每生成4 mol N₂，转移电子数为15 n_A

D．电解精炼铜时每转移n_A个电子，阳极溶解32 g铜