核潜艇上备有的氧气再生药板,是由一片片涂有过氧化钠(Na2O2)的薄板组成,使用时Na2O2与CO2反应,反应的化学方程式为:2Na2O2+2CO2→2M+O2,则M的化学式为
--- What is your favourite sport? --- Swimming, I think. It's of all.
---I use your ruler, Lingling? --- Sure. Here you are.
--- Do you like watching TV? ---Yes, I. But only after I finish my homework.
Li Yan is my best friend. She comes a small village.
How is your father? Please say hello to ______ for me.