Don't do any other things while you are doing your homework. So please _________ your MP3.

 One day, when your mother gets older and older, will you dislike her more words and her had health? Here is a mother's letter to her1. Let's read it and see what's moving you.

Dear son,

 When I grow old one day, please be 2 to me and try to understand me. If I get dirty when eating or if I can't 3myself, help me. Remember the hours I spent teaching you . If I say some things again and again when I speak to you, please4me. When you were5, I had to read you the same story again and again 6 you went to sleep. When my tired legs do not let me walk, give me your 7. I did the same when you started walking. When I come near to you, you should be next to me, try to understand me and help me 8 I did when you were a baby. When I am ill, you should look 9me well, just like I took good care of you day and night. Please spend more time10 with me when you are free. I`ll pay you by a smile and love.

I love you, son!

                                                               Your mother,

                                                               Mary

Cu₂O是一种半导体材料，可用电解的方法制取。电解示意图如下，电解总反应为：2Cu+H₂OCu₂O+H₂↑ 。下列说法错误的是（      ）