My name is Tom. I come from England. I like to have friends who are different from me. My best friend is Paul. Paul is funnier, more outgoing and athletic than me. He always tells jokes and makes me laugh. We also like different things. He likes going to the movies. He likes playing sports. He likes pop music. But I like reading books. He often asks me to go to the movies and gives me some interesting books. And I often give him CDs. We often help each other.

    My best friend and I……

除去下列物质中含有的杂质所选用试剂或操作方法不正确的一组是（　　）