题目

We went through a period _____ communications were very difficult in the rural areas. A．which        B．whose          C．in which          D．with which 答案：C下列说法正确的是(　　)? A.摩尔是6.02×1023个结构粒子的集体? B.每摩尔物质含有个指定的结构粒子 C.0.012 kg12C所含的原子数正好是6.02×1023?? D.摩尔是表示物质的量的单位