在大体积墩台混凝土中掺入25%的块石,是为了加快施工速度。 ( )
参考答案:错
下列变化中,属于化学变化的是 [ ]
A. 水沸腾变为水蒸气
B. 石蜡熔化
C. 工业上用空气为原料制氧气
D. 钢铁生锈
— You aren't a student now, are you?
— _____, don't you remember _____ me in the classroom ten minutes ago?[ ]
A. No; seeing
B. Yes; seeing
C. No; to see