进行垫垛作业时,仓管员要注意()
A.地面要平整夯实
B.垫基要摆平放正
C.垫基要保持一定的高度,间距适当
D.要注意垫底材料的排列方向,利于通风
参考答案:A, B, C, D
They have saved 90 people, _____ last year. [ ]
A. twice of many
B. twice as many as
C. twice more
D. twice as much as
孕妇需避免X线检查,是因为()。
A.X线的光化学效应
B.X线的荧光作用
C.X线的生物效应
D.X线的感光作用
E.以上都不是