哪些介质属易燃介质？
参考答案：
与空气混合的爆炸下限小于10%，或爆炸上限和下限之差值大于等于20%的气体。
—Could you tell me ________ the party?
—Next Friday.
A. where we are going to have
B. when we are going to have
C. when we were going to have
原子论最初的提出者是：（）.
A、德谟克利特
B、赫拉克利特
C、巴门尼德
D、亚里士多德
