运输成本结构有哪些?
参考答案:运输成本结构:变动成本、固定成本、联合成本和公共成本。
The book ____ forty maps, three of Great Britain ____.
A.is containing; includes
B.contains; included
C.contains; including
D.includes; contains
门窗框安装时采用锚固铁脚固定,下列有关“铁脚”的说法错误的是()
A、铁脚必须经过抗拉试验
B、其间距不得大于500mm
C、铁脚必须经过防腐处理
D、宽度不得小于25mm