—Haven't I told you that you should be home earlier?

—Yes, but I ________ home earlier than I usually do.[ ]

A. was coming  

B. will come

C. came  

D. had come

土壤胶体的特性有（）

A.巨大的比表面和表面能

B.带电荷

C.土壤胶体具有凝聚性和分散性

D.稳定性