下列气体遇明火不可能发生爆炸的是（ ）
A．氢气和空气混合
B．面粉粉尘和空气
C．液化石油气和空气
D．氢气和氮气混合
答案：D
—________ I go out to play now,Mum?
—No, you ______.You should do your homework first.[ ]
A. Must ; mustn't
B. Must ; wouldn't
C. May ; needn't
D. May ; mustn't
大型消费者（macroconsumers）
