地震区的高层建筑，平面以方形、矩形、圆形、三角形为好。
参考答案：错
There were 20 people sitting in the room, half ___ were women.
A．of whom
B．of which
C．about that
D．about whom
水泥安定性是反映水泥硬化后（）变化均匀性的物理指标。
A.凝结时间
B.体积
C.掺加量
