Wang Pin is an advanced worker in our company. He _______ for four years in Yangzhou University.

A．studied

B．has studied

C．had studied

D．has been studying

（）是制造企业生产过程中的辅助生产过程，它是工序之间、车间之间、工厂之间物流不可缺少的重要环节。

A.工艺布置

B.设施布置

C.物料搬运

D.运输成本