网架顶升法施工是( )。
A.将网架结构在地面上总拼
B.在架子上拼装
C.用起重机安装到设计标高
D.用网架上的起重设备提升就位
E.用网架下千斤顶顶升就位
参考答案:A,D
某元素最高正价与负价绝对值之差为4,该元素的离子跟与其核外电子排布相同的离子形成的化合物是[ ]
A.K2S
B.MgS
C.MgO
D.NaF
A firm operating under perfect competition will experience economic losses when which of the following conditions exists()
A. Marginal revenue is greater than average total cost.
B. Market price is less than average total cost.
C. Marginal cost = average total cost = marginal revenue = price.