用下列方法制取O₂：①KClO₃（MnO₂）受热分解；②Na₂O₂加水；③H₂O₂中加MnO₂；④KMnO₄受热分解，若制得相同质量的O₂，反应中上述各种物质（依编号顺序）的电子转移数目之比是（　　）

⑴Where are your parents?____                           A. Yes, I'd like some fruit.

⑵Is your brother sleeping in the room?____      B. They are at home. 

⑶Can I help you?____                                         C. She's playing the piano.

⑷Would you like some fruit?____                       D. No, I'm not.

⑸Can you see the red light?____                        E. She's singing.

⑹What is Helen doing?____                                F. Yes, please.

⑺Are you busy?____                                           G. No, I can't.

⑻What is she doing in the music room?____     H. No, he isn't.