加工活动和物流活动是生产系统的（）。没有加工，生产系统就失去存在的意义；没有物流，生产系统将会停顿。

A.两个独立部门

B.两个支柱

C.下属机构

D.重要环节

— It was careless of you to have left your clothes outside all night.

— My god! _______. [      ]

A. So did I

B. So I did

C. So were you

D. So did you