题目

—Must we finish the work today?—________. We have something else to do tomorrow. A . Yes, we can B . No, we can't C . Yes, we must D . No, we needn't 答案：C 若1 mol 某气态烃CxHy完全燃烧，需用3 mol O2，则(　　) A．x＝2　y＝2　　　　　　              B．x＝2　y＝4 C．x＝3　y＝0                          D．x＝3　y＝4