题目

某有机物M在足量氧气中充分燃烧后的化学方程式如下：2M + 13O2 === 8CO2 +10H2O。则M的化学式为A．C4H10B．CH4 C．CH4OD．C2H4O2 答案：A解析:略We should respect food and think about the people who don’t have _______ we have here and treat food nicely. A. that　　　　　 B. which　　　　　 　 C. what　　　　　　 　 D. whether