直肠瓣有阻止粪便排出的作用。()
参考答案:对
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