低温养护中药可以防止饮片（）

A.生虫

B.霉变

C.变色

D.走油

E.散气

—Hi，Jim. I_______ you for a long time.     

—I_______ in Beijing for two months. I’ve just comeback.    [      ]

A. didn’t see; have been                

B. haven’t seen; was    

C. didn’t see; was                      

D. haven’t seen; have been