More than 10,000 relics, ____ between 5,000 to 3,000 BC, ____ at Sanxingdui since it was first discovered.

A．dating back to, was dug up

B．dating back to, have been dug up

C．dated back to, has been dug up

D．dated back to, were dug up

生产场所的工位器具、工件、材料摆放不当，不仅妨碍操作，而且容易引起设备损坏和伤害事故。为此要求( )。

A．一般摆放方位同墙或机床轴线平行，尽量堆垛成正方形

B．工件、物料摆放不得超高，在垛底与垛高之比为1:2的前提下，垛高不超出3m

C．堆垛的支撑稳妥，堆垛间距合理，便于吊装，流动物件应设垫块且楔牢

D．产品坯料等应限量存入，白班存放量为每班加工量的2.5倍

E．生产场所的工位器具、工具、模具、夹具应放在指定的部位，安全稳妥，防止坠落和倒塌伤人